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Post by Admin on Apr 11, 2022 19:18:55 GMT
Firstly, continuing mixing of British/Welsh metal with East Alpine metal would lead to a homogenisation of the trace element contents and the lead isotope ratios, and thus result in a fairly homogeneous geochemical fingerprint–leading, in other words, to concentration of a large number of artefacts around the same ratios (see Fig 9). A few axes could be allocated directly to English/Welsh ores based on their isotopic and chemical fingerprint: three axes from Bækbølling (#182), Lavesgård (#167) and Højme (#162) fully match the Alderley Edge mine in England [39], which was probably in use at least until the first half of 1600 BC [98–101]. The axe from Brørup (#186) and another axe (#106) closely match the signatures from Great Orme in Wales, where nickel-arsenic metal was extracted specifically during the Middle Bronze Age [36,37,102]. Secondly, the majority of group 3 shaft-hole axes show higher Sb–Ag concentrations (Fig 11) than can be recognised in the Great Orme ores, and significantly higher values than measured in the slag prills from Pentrwyn, Llandudno [36,37]. Although more detailed knowledge is still required of the trace element composition of relevant British sources, it can be stated that the many shaft-hole axes of group 3 were probably cast from mixed metal following a trend already identified in NBA IA and LN II [1,2]. This new insight could only have been gained through the evaluation combined above of stylistic features (local production), chemical composition, and isotope ratios. The mixing is well illustrated in Nordic shaft-hole axe #108, which isotopically would be identified as Welsh, while chemically mirroring the metal mined at Mitterberg (Fig 11).
To sum up: The typological and geochemical uniformity of Fårdrup-type shaft-hole axes turned out to hide complexity in provenance patterns. Group three, the largest with 49 axes, revealed local mixing of copper from British ores and from Mitterberg in Austria. Two shaft-hole axes analysed elsewhere [6,8] show very similar values. One axe from Denmark was connected to British ores by Melheim and colleagues [8]. The other Fårdrup-type axe, however, from Ny in Sweden (AM786), had previously been seen as evidence for Cypriot metal in Scandinavia [6]. It should now rather be integrated in this group of axes, with signs of mixed East Alpine and British ore or artefact metal. Mitterberg provenance could also explain isotope group 2 with fourteen axes, while group 1 with only four, showed a clearly deviating pattern compatible with Italian AATV copper. The fact that Valsømagle-type axes, in total seven, were present in all three groups raises the question of possible chronological differences between these two artefact types, aside from their obvious belonging to dissimilar craft traditions.
Could chronology, then, have co-determined the three isotope groups against the backdrop of the clear bipartite division between shaft-hole axe types? In the absence of new absolute dates, establishing a fine-meshed chronology for the two shaft-hole axe forms is problematic; but the compositional patterns described above, interpreted in conjunction with archaeological methods, can provide some indications. Remarkably, Valsømagle-type shaft-hole axes occur in all three groups, which may indicate parallel tracks. Isotope group 1 is particularly noteworthy for its clear Italian AATV isotopic signature, and additionally because inspection of the metal-analytical pre-1600 BC data of objects shows no Italian metal in southern Scandinavia this early [1,8]. The axes of group 1 might then emanate from AATV arrivals as early as late NBA IB, or they could be later, continuing into early NBA II after 1500 BC. Isotope group 1 of AATV provenance comprises two Fårdrup-type axes (#160, #168, Supplement1) and one Valsømagle-type axe (#269). It also includes a Carpathian-style disc-butted shaft-hole axe (of B type, #270), stylistically dated to NBA II around 1400 BC [103], which substantiates the late chronological position of this isotope group.
In conclusion, both Valsømagle-type shaft-hole axes and Fårdrup-type shaft-hole axes occur spread across all three metal groups, eluding definite chronological conclusions [20,95,104]. Nevertheless, even if it is distinctly later than Fårdryp-type metalwork, one might have expected Italian Alpine AATV copper to have been prominent among the Valsømagle items. According to current knowledge, this is not the case. This discussion, however, raises the question of when Italian copper first arrived in the NBA zone, and in what form. Research has so far not been able to identify copper of northern Italian (AATV) provenance in Scandinavia prior to NBA II.
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Post by Admin on Apr 11, 2022 21:01:12 GMT
4.4.2 On the track of north Italian AATV metal 1600–1300 BC. Artioli and colleagues [34,75] have recently pointed out the clear importance of the copper deposits in the Italian Alps for the international Bronze Age trade. The arrival of copper to Scandinavia from the AATV region has so far been dated to NBA II [7,50]. When did the AATV copper begin to arrive more regularly, and in what proportions relative to other coppers arriving in Scandinavia? The much larger dataset now available on artefacts and on the major mining areas will help to provide answers to these questions. Several other copper sources than AATV could well have supplied long-range trading enterprises prior to and during NBA II. Recent studies notably identify Austrian, Slovakian and British copper sources 1600–1300 BC [7,8,50]. Long-distance transport of metal to southern Scandinavia is well attested during the first third of the second millennium BC both from the British Isles and from a select few mining sites in central Europe, namely the Inn Valley in the eastern Alps and the Slovakian Ore Mountains [1,6,8]. Although copper deposits in Germany are common, evidence is lacking that they were known and exploited in the Bronze Age: when the provenance of the metals used for the Nebra hoard was investigated, it was possible to exclude most of these copper occurrences as possible sources [25,105]. For the Alpine region more generally, the situation is optimal, because the many adjacent Bronze Age slag sites [73,106–108] reveal, for example, that the technology of copper production in the Italian AATV and the Austrian Alps was quite similar [74,109–117]. Besides, the large volume of lead isotope data from these two Alpine regions [29,30,32,34,73–75] allows for distinctions to be made between them despite their similarity in trace element composition. A well-illustrated example of this new potential concerns the metal objects of the burial of a wealthy woman at Ølby on Zealand, dating to 1400–1300 BC in NBA II. Three items were analysed, revealing similar trace element concentrations. However, the significantly different lead isotope ratios resulted in the suggestion that the copper of which the Ølby items were made originated from three different sources [118]. The most promising approach for tracking the arrival and significance of Italian AATV copper in southern Scandinavia is to compare lead isotope ratios with stylistic information. Isotopically, there is no evidence within the dataset for AATV copper prior to 1600 BC. During NBA IB (1600–1500 BC), only a few artefacts of local Nordic production isotopically match the signatures of the AATV region (Fig 12), namely, the shaft-hole axes #160, #168 and #269, in addition to four high-flanged axes distributed across Denmark (#83, #84, #90, #111). Thus, in NBA IB (1600–1500 BC), Italian ore is represented by seven objects–or four per cent of the analysed material from this period. Seen in the light of the substantial rise of AATV copper in NBA II, that four per cent is remarkable. Fig 12. The data evaluation illustrates that Italian AATV copper may have been first used in in southern Scandinavia from NBA IB (1600–1500 BC). Its importance increased drastically towards the mature NBA II c. 1500–1300 BC, and from 1450 BC Italian AATV copper seems to dominate the metal supply. This study shows that probably 40% of the artefacts were made of this copper, while for 23% evidence for mixing metals with other sources is possible. At the threshold to the mature NBA II, c. 1500–1450 BC [10,11,104], a rising inflow from AATV copper sources may be indicated by the isotope analysis of eight developed high-flanged axes of Oldendorf type [4], of which two were assigned an AATV provenance. In continuation of the Valsømagle spiral-decorated metalwork, this transitional phase into NBA II is a further step towards the full stylistic conceptualisation of NBA II during which the AATV provenance becomes distinct (Fig 12). This happens in tandem with the Central European Tumulus Culture Br.B-C and indeed through cultural exchanges with the Aegean world [119–121].
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Post by Admin on Apr 12, 2022 18:48:53 GMT
4.4.3 The wider panoply of low-impurity chalcopyrite-like copper in NBA IB and NBA II. Fig 4 demonstrates that artefacts dating to NBA IB and NBA II belong to only two to three trace elemental groups (clusters). In NBA IB, 90% is low-impurity copper (C#5/11-C#6), which may be termed sulphidic copper, indicating chalcopyrite-dominated ores. In NBA II, 96% of the analysed artefacts are classified as low-impurity copper. The small remainder group consists of C#2 fahlore. In fact, Nordic use of high-impurity copper (fahlore cluster C#2, C#3, C#7) decreases continuously over time. The full conversion to low-impurity copper around 1600 BC is no doubt significant, albeit the apparent uniformity of trace elemental concentrations hides complexity in provenances, as already demonstrated by the shaft-hole axes. NBA IB 1600–1500 BC. Only ten NBA IB artefacts are made of high-impurity copper. Their trace element composition is strikingly similar to the fahlore deposits in the Slovakian Ore Mountains so favoured in LN II and NBA IA [27,28] (Fig 13). These apart, the NBA IB artefacts are made of low-impurity copper. For the extensive group of shaft-hole axes, our tracking of the provenance of their copper to different Alpine and British sources is presented above: in many of these massive axes, we found evidence of mixing copper from British and Mitterberg ore sources. As stated above, only in a few instances was a match found with AATV lead isotope signatures. The 60% of the NBA IB artefacts of the low-impurity copper group that are not discussed above are locally produced high-flanged axes and a few slender weapon-flanged axes, a flanged chisel (classification based on [4]), and five spearheads, including three Bagterp-type spearheads (#288–290) and one Valsømagle-type spearhead (#262) from the eponymous hoards. This new lot displays the same isotopic diversity and can be allocated to the same clearly defined groupings identified above as the shaft-hole axes. Fig 14 reveals more details. Fig 13. Diagram of Sb/Ag of the NBA IB artefacts consisting of high-impurity copper compared to the low-impurity copper C#6. The Sb/Ag concentration suggests an origin for the fahlore copper in the Slovakian Ore Mountains, while the low-impurity copper is consistent with the tendencies discovered for the shaft-hole axes and point to East Alpine copper. The ore data are from: Mitterberg ore district [35], Hron Valley, Slovakia [27,28], Inn Valley/Buchberg, Alpine region [29,30], Great Orme mining region, Wales [36–39]. More precisely, in analogy with the shaft-hole axes of isotope group 2, 28% of the high-flanged axes analysed, with 206Pb/204Pb values far above 18.53 and 207Pb/204Pb values from 15.65, are in line with values from the East Alpine deposits. Further, a group of items made of low-impurity copper probably from the Slovakian Ore Mountains is now distinctly visible in the full dataset for NBA IB; in the large group of shaft-hole axes, this signature was suggested by two Valsømagle-type shaft-hole axes (#102, #268). Thus, by NBA IB, Slovakian low-impurity chalcopyrite copper is distinctly present in the metal stock–having first appeared in very small amounts as early as LN II and having increased markedly during NBA IA [1] (Fig 14). NBA IB even shows a very low presence of “old-fashioned” high-impurity fahlore copper from the same region (Fig 13). The isotopical and elemental overlap within this isotope group 2 (see 4.4.1), however, suggests that mixing of different low-impurity copper sources or artefacts is an option. Furthermore, a large and dense group consisting of 67 artefacts including high-flanged axes and the spearheads #262, #288–90 and #306 is identified and is comparable to the 47 shaft-hole axes of isotope group 3. The isotopic ratios of these artefacts match the signatures of British and Welsh ore deposits (Fig 14). Even though the flanged axes generally show higher silver values and therefore present Sb–Ag ratios more likely compatible with Great Orme [36,87], the majority of these artefacts escape further classification because their trace elemental values lie in between the known trace element composition of East Alpine and Welsh deposits. By analogy with the shaft-hole axes of isotope group 3 and with cases of intentional reuse of LN II–NBA IA artefacts [see 1,2], this could tentatively be explained by mixing. Alongside the evidence for Great Orme metal, a small assembly of nineteen (15%) artefacts in addition to the three shaft-hole axes identified above indicates a west European origin, but these favour the Alderley Edge mine in Cheshire [39]. The trace element composition of this group does not exhibit any characteristic signature that would allow an allocation to Austrian or Slovakian ores [see 27,28,30,35]. However, state-of-the-art data regarding the trace element concentrations of the English ores around Alderley Edge does not allow any definitive allocation to this source. In light of this evidence, we propose that despite the decline in identifiable copper clusters, the period from 1600 to 1500 BC (NBA IB) evidences the onset of a much more extended trading network, capable of satisfying the distinctly increased demand for metal in a metalwork production which already reveals early trends in what was to become the classic, emblematic NBA II brand at c. 1450 BC. Alliances with long-standing trading partners in the Slovak region were maintained, but a major new thrust now targeted the East Alpine region, while trading relations with the British Isles intensified compared to LN II–NBA IA levels. Close to 1500 BC, with the first importation of Italian AATV copper, new trading links become visible. NBA II Early 1500–1450 BC. The period around 1500–1450 BC is one of transition to the full-grown NBA II [10,11,89,96]. Already the main ingredients–repetitive mound-building and accomplished metalwork–are in evidence, including spiral symbols in continuation of Valsømagle-type weaponry. Even though only few artefacts dating to the transition period have been sampled, it is significant that they show isotopic diversity in the low-impurity copper (of cluster C#5; C#6). This recalls NBA IB in addition to the classic NBA II, the latter through the presence of Italian AATV copper. NBA II Classic 1450–1300 BC. The full-grown emblematic style–pivoting around an array of spiral patterns and a clear-cut vocabulary of items for men and for women–emerged sometime between 1450 and 1400 BC. The formation process was probably in place around 1450 BC, because the much-cited dendro-dated group of oak coffin burials, 1400–1300 BC, is a geographically and chronologically constrained tradition involving mound-building with so-called iron pans to protect the dead [49,122,123]. The majority of the NBA II artefacts investigated in this study derive from NBA II Classic [12,124], and on this basis can be dated relatively precisely, namely to 1450–1300 BC. The lead isotope ratios suggest that 63% of the samples in our suite (57 swords, ornaments and tools) have signatures compatible with the Italian Alpine region. This confirms a trend noted in recent studies [7,8,50]. These samples consist of Italian AATV metal in local metal production in southern Scandinavia (Fig 15A), for example, the Ølby beltplate #275, the two large belt plates from Frankerup #231 and #257, and nine other belt and neck ornaments (#227, #229, #237, #248, #250, #263–264, #266–267, #291). So far, only a single sword blade and disc-butted axe show values similar to the ornaments (#240 and #270). All these artefacts disclose 206Pb/204Pb values lower than 18.25 and 207Pb/204Pb values above 15.63, also found in contemporaneous northern Italian artefacts shown to originate in the AATV mining region [125]. This further corroborates the AATV provenance.
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Post by Admin on Apr 12, 2022 20:09:00 GMT
Fig 15. 206Pb/204Pb/207Pb/204Pb diagram of NBA II artefacts analysed within this study, compared to contemporaneous artefacts. (A) compares the ornaments and swords with the most probable Central and South European ore deposits. Consistent with contemporary artefacts with secured AATV provenance (data taken from [125]), a large group of artefacts is comparable with South Alpine Italian deposits. Artefacts of the Ølby burial, sword #273, neck collar #274 and belt plate #275 are highlighted. (B) compares NBA II artefacts with artefacts of proved Slovakian provenance (data taken from [8,50,51]). The Ølby neck collar #274 and the spearhead from Ullerslev #272 are probably made of Slovakian low-impurity copper. (C) shows that the majority of the artefacts analysed elsewhere (data from [6–8]) fall within the range of the Italian AATV deposits consistent with the data presented here. A significant group (marked) can, at the present state of research, only be defined, but not provenanced. The sheet-tubes (VM1680) from Vognserup Mose [8] and the octagonal-hilted sword MA-071206 [51] are highlighted, plotting an area where several Welsh deposits are present. The ore data are from: Hron Valley, Slovakia [27,28], Inn Valley and Buchberg, Alpine region [29,30], Italy AATV mining region [32,73–75]. The analytical uncertainties are comparable with the size of the symbols. A portion of our dataset–eleven artefacts–pinpoints Slovakian low-impurity sulphide deposits: neck collar #274, the belt plates #224–226, #234 and #293, #297, the sword hilt #241 and blade #223, #246 and the spearhead #272. Lead isotope ratios support this provenance (Fig 15B), as does the trace elemental composition, especially the As–Sb ratios. The neck collar from the Jægersborg burial #238 is made from high-impurity fahlore with Slovakian signatures. Over and above the investigation presented here, several swords dating to the classic NBA II have been investigated by Bronze Age scholars in the last years [7,50,51,126], confirming the use of Slovakian low-impurity copper in sword production (Fig 14B). While, surprisingly, only two artefacts in our study–the sword from the Ølby burial #273, and a small belt plate from the Vognserup deposition #294 –can be linked to East Alpine ore deposits at Mitterberg, up to twelve swords from the above-mentioned studies, found predominantly in northern Germany and Denmark, show isotope and trace elemental patterns related to this East Alpine deposit [50,51]. There remain a large number of analyses (23%) with no clear match, either with the Italian ores or with comparable Italian artefacts (Fig 15C). Isotopically, these artefacts can be compared with the values known from Miniera Bedovina in the Trentino [75], the East Alpine Inn valley [29,30] and the Slovakian Ore Mountain ores [27,28]. Definitively stating a provenance for this group, however, is a challenge, given its higher antimony values than known from the East Alpine deposits or the Welsh ores. In the comparative literature [7,8], swords and ornaments with similar isotopic ranges are allocated to Italian AATV deposits. However, once these are compared with the new data presented here (Fig 15C), a significant proportion fall within the isotopically undefined area, including the sheet-tubes from the Vognserup hoard, previously interpreted as made of Iberian copper [8]. This raises questions about the significance of Mediterranean copper in Northern Europe between 1600 and 1300 BC. The Nordic Bronze Age formed part of a bronze-driven Afro-Eurasian intercommunity from 2100–2000 BC onwards. Baltic amber was reaching Mediterranean urban hubs in significant amounts as early as 1600 BC and continued to flow over the next centuries. Given this, it would not be surprising to find Mediterranean copper in the Nordic metal data, as has been suggested by the Moving Metals project [3,6–8]. Researchers in the present study share ideas regarding the amber-for-metal trade with Ling and colleagues. We are fully in agreement on the extension of the trading network towards southern central Europe in NBA II, a conclusion that rests on corresponding data from Sweden, Denmark, Norway, and northern Germany, all of which pinpoints the presence of Italian AATV copper in NBA II [7,8]. The Moving Metals project claimed to identify Spanish, Portuguese, Sardinian and Cypriot copper in the production of a number of Nordic artefacts, notably some shaft-hole axes as well as high-flanged axes of Underåre-type [6] in NBA IB, 1600–1500 BC. One NBA II sword from Odsherred in Holbæk county analysed in the Moving Metals study revealed high 208Pb/206Pb and 207Pb/206Pb lead isotope values, which were interpreted as indicating a possible Sardinian origin of the metal [7]. However, the present study, based on more than 500 samples, has not been able to detect copper of Mediterranean or Iberian provenance in the analysed first 700–800 years of the Bronze Age in Denmark. If a pool of this metal had been available locally, Mediterranean signatures would have been identifiable, particularly among the female ornaments measured. Unlike swords, the ornaments of the Nordic Bronze Age, such as belt plates and neck collars, are stylistically and technologically restricted to southern Scandinavia [47,49]. Accordingly, they most certainly are local products, and their metal must have been imported, but not the artefact itself. Swords do not always define a local production. The first swords in southern Scandinavia arrived around 1600 BC from south-east Europe. They were traded from the Carpathian basin and Transdanubia as far as Middle Sweden and northernmost Denmark and were often recast locally as lookalikes [20,41,50,127–129]. A similar pattern in sword production is found in the developed Bronze Age: distinct sword types are widely distributed across parts of Europe, and a specific local production is hardly visible [130,131]. Thus, the metal of swords will not necessarily illuminate the metal trading networks behind local metalcraft as clearly as with ornaments. The group of analyses that elude clear identification even though the range of trace elements and isotope ratios is broadly compatible with central European ores includes several artefacts for which a Mediterranean or Iberian origin has been discussed [6–8]; but at present, in view of the intense local mixing, a more precise identification is unreachable. It seems, though, that west European metal may have played a role in this process (see Fig 15C), as the octagonal-hilted sword (MA-071206, [50]) and the sheet-tube from Vognserup (VM1680HS, [8]) could probably consist of Welsh metal. Considering that British and Welsh copper always played a role in southern Scandinavian metallurgy, one is tempted to explain the mixed signatures of these artefacts in terms of the continuous remelting of the metallic material culture. To conclude: From 1600 BC, almost all the substantial quantities of metal reaching Scandinavia are to be classified as copper smelted from sulphidic ore, dominated by chalcopyrite. Despite a striking uniformity, scrutiny of the trace element components and isotopic signatures have revealed a diversity contingent on the origin of the metal. In NBA IB 1600–1500 BC, a wide array of provenances are present: the eastern Alps at Mitterberg, Great Orme in Wales, Alderley Edge in central England, and finally the Slovakian Ore Mountains in continuation of an earlier tradition. By comparison, Italian AATV is only just discernible in the data. The transitional phase to classic NBA II is transitional also in terms of its copper imports, and AATV seems to have been on the rise. During classic NBA II, 1450–1300 BC, Italian AATV copper rises markedly to over 60%, followed by the old acquaintance of Slovakia. The data of this study indicates that south-east Alpine AATV copper was the most southerly supplier for Danish metal production from the onset of NBA II–with a tiny beginning in NBA IB.
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Post by Admin on Apr 12, 2022 20:54:11 GMT
5. Conclusion The novelty of this study rests on the large number of early metal artefacts investigated from the early phases of the Neolithic through to the established Nordic Bronze Age. A representative coverage is especially relevant to the Bronze Age periods 2100–1300 BC. It has been possible to identify the major sources of metal arriving in each period (S1 Fig), and additionally to track how changing provenances tie up with new artefact styles and most likely with new forms of social organisation. More precisely, the inquiry has shown a tight relationship between early metal use in each major period and changes in the provenance and class of copper arriving in southern Scandinavia. Furthermore, as will be elaborated in the paragraphs that follow, these shifts in metals entailed reorganisation not only in the long-distance routes of transfer, but also, through responses to changed geopolitics at a European level, in the societal setup in the north. The dating of these transitions by the associated archaeological material is not sufficiently precise to demonstrate with certainty whether the changes happened at the same time or sequentially over the period in question. In either case, however, causality is involved. In the light of the analytical results described above, the configuration of several changes is indeed significant. Before the advent of the Bronze Age c. 2100–2000 BC, material culture in the Neolithic is characterised by on-and-off presence of items of copper and gold. The two Neolithic periods with a faintly discernible rise in metals are the Funnel-Beaker culture of the mid-fourth millennium BC and the Bell-Beaker-affiliated LN I in the later third millennium BC. For both periods, metallurgical experiments likely contributed to increased interest in metal items, with the clearest evidence in the earlier period [4,13–15,52,132]. The present study has provided new insights into the Bygholm type of metalwork made of arsenic-rich but otherwise pure copper: the new analyses have revealed a strong connection with south-eastern Europe. This prevalent Riesebusch-Mondsee copper is likely consistent with copper mines in Serbia and/or Bulgaria. We can therefore point to a link between southern Scandinavia and south-eastern Europe’s rich Chalcolithic, however in all likelihood with the Austrian Mondsee group as mediator of copper to the north. The Bygholm metalwork appears to form part of the new networks that enabled the establishment of a fully Neolithic society in southern Scandinavia. Its appearance coincides remarkably with the appropriation of other novelties, such as jadeite axes, long barrows, causewayed enclosures and, eventually, megalithic monuments of dolmens and passage graves [15]. The Bell-Beaker-related copper differs radically from the uniform Riesebusch-Mondsee copper. It is isotopically and compositionally so diverse that a single provenance seems unlikely. The later Earlier Neolithic and the entire Younger Neolithic with Corded Ware migrations (3500–2300 BC) are often described as periods devoid of metals. However, the analysed dataset hints that isolated prestigious copper axes did find their way north even in the long intermediate periods of the Neolithic. More research is required to probe into this question and the extent to which metallurgical knowledge accompanied the arrival of metal items in the Neolithic [15]. In relation to the clear and continuing increases in copper imports to southern Scandinavia from 2100–2000 BC onwards, Neolithic copper use was insignificant. That fundamental change denotes a transition from predominantly regional transmission of commodities among fairly autonomous Neolithic societies to a fully globalised Bronze Age economy entirely reliant on long-distance trading of copper and tin [18,19]. This dependency transformed societies irreversibly as regular metal supplies became necessary for the political economy to survive intact. In fact, the transition 2100–2000 BC was the point of no return. The evidence of regularly shifting ore sources and relocation of the transfer routes in operation at different points in time may indicate that Bronze Age hyper-connectedness had innate weaknesses, with associated consequences for the local setups of power. Shifts in one part of the system had the potential to impact other, even distant parts. In the period 2100–1700 BC (LN II), three supply regions are identified (see S1 Fig): the eastern Alps, Slovakia, and the British Isles [1,2,133]. First to arrive, by way of EBA hubs in Únětician central Germany, was high-impurity fahlore copper from the Austrian Inn Valley and from the Slovakian Ore Mountains, in quite large quantities. This was at the height of the Únětice culture, which boasted princely graves as well as enormously rich hoards such as Dieskau 2 at Halle-Saale, which contained Baltic amber in addition to numerous metal objects [134]. Abundant amber in the metal-rich cemeteries of Bohemia (Czech Republic) indicate that Baltic amber arrived there along this eastern route, but apparently it did not go any further [45,135]. At the same time, a western sea route linked southern Scandinavia with the British Isles and provided desired high-tin copper in exchange for Baltic amber (found in clusters in the rich EBA graves of the Wessex region of Wiltshire [17]). Back home, the growing production, consumption and circulation of metals provided comparative advantages in the competition for sociopolitical leadership. These are visible in the building of ancestral gallery graves for collective burial, over-size longhouses, hoarding of metal objects, and metal-led material culture more generally. Most of these manifestations can be considered a compromise between a rooted communal tradition and new leadership forms emerging from the metal enterprise [17,21]. Imports into Scandinavia took place in the form of rings and axes, treated as ingots [1]. Low-Ni fahlore copper mined in the Inn Valley of the eastern Alps was traded intensively, shaped in the characteristic Ösenhalsringe form. The 30% high-tin artefacts in LN II underline the importance of English and Welsh copper in local Nordic metal production. Practically, imported large British bronze flat axes were mixed with hack metal from the Inn Valley and Slovakia: the geochemical traits of British copper deposits identified in objects of local Scandinavian styles, such as the Værslev/Æbelnæs-type axes from Valore #33 and Æbelnæs #39 on Zealand, confirm the remelting of foreign artefacts into products suited to local taste and demand. The extreme high-tin (10–14%) content of the British bronze flat axes was especially sought after [1,2,17], and must have prepared the ground for the full adoption of tin-alloyed bronze from c. 1700 BC. This robust evidence for the implementation of British-Scandinavian trade as early as 2000 BC is fresh and recent. Beginning c. 1700 BC, NBA IA is a period of metallurgical and military innovation. This is manifest in standard tin-bronze alloys and the numerous socketed spearheads that were now in production. NBA IA is also about crisis, apparent in the abandonment or reorganisation of settlements with traditional two-ailed longhouses [136]. Importation of British artefacts is no longer in evidence, even though British and Welsh metal is a well-used source in local southern Scandinavian metalwork, as shown in the increased tin-values of the elaborated axes. A British signature still transpires in the dataset of metals, which now comprise nearly two-thirds Slovakian fahlore well-known since LN II and one-third of novel low-impurity chalcopyrite-like copper, also from the Slovakian Ore Mountains (see S1 Fig). This mélange, visible in the trace element patterns and the lead isotope ratios [1], may stem in part from the local production practice, seen clearly in LN II, of one-to-one mixing of artefact metal from different sources. Increased recycling would be consistent with changing geopolitics in non-Mediterranean Europe at the threshold to the Middle Bronze Age. A part of the Slovakian fahlore could thus be recycled from LN II, which would explain the British traces. However, the Slovakian chalcopyrite-like low-impurity copper demonstrates that new loads of metal did reach Scandinavia at some point during the seventeenth century BC. By now, tin is standard, but its provenance is unknown: it could be either from Cornwall or from the Erzgebirge mountain range. Many societies changed culturally and socially in the seventeenth century BC, but given current knowledge, it is hard to pin precise social labels and timelines on this change in northern, western and central Europe. This is the period of the demise of the formerly prominent Únětice culture, which disappears from the record c. 1600 BC [46]. The metal-for-amber trade must have collapsed as the reliable economic basis for the contributing persons or groups [137–139]. But by the same token, with the tight control of this trade formerly exercised by the Únětician bottleneck dwindling, the path opened towards the resource-rich crossroads in the Carpathian basin, for the Scandinavians as for others: the amber-for-metal trading network, begun in LN II, extended its range in NBA IA towards the south-east [45]. The plentiful Baltic amber in the Mad’arovce-Věteřov cemeteries of south-west Slovakia at the transition from EBA to MBA [45,140] verifies that the eastern route did not disappear. It may well have been destabilised, but it was extended nonetheless. Much of the metal reaching southern Scandinavia at this time went into spearheads. The lengthening of the eastern route accords well with the origin of the spearhead idea in the Carpathian basin (ultimately the Steppe Zone) and with the first arrival of chalcopyrite-like copper in Scandinavia from Slovakia. These transactions likely interwove with new social ideas, stimulating local metal production to keep pace with innovations. The demise and the final collapse of the Únětice culture may have brought with it some shortage of metals in the north, possibly accounting for the suggested increase in the reuse of existing metals. Another indicator in support of such a scenario is the new developments in the succeeding period, when the Carpathian connection becomes even more distinct. By NBA IB, the visible boom in copper imports to Scandinavia is coeval with near-industrial mining in major ore fields, which took off in the sixteenth century [35,41,141,142]. The dataset further points to a much-extended trading network (see S1 Fig). The more than two hundred artefacts analysed from this first breakthrough of the NBA strongly indicate the reorganisation of the trade towards routinisation and commodification, likely with separate ingots for copper and tin. This is the conclusion that emerges from the dataset, showing British metal once again playing a central role in Scandinavia. Albeit there are no metal objects imported from the British Isles, there is clear evidence of much-increased use of English (Alderley Edge) and especially Welsh (Great Orme) copper. Clearly, the sea route between southern Scandinavia and the British Isles had been re-established, now probably carrying ingots. The overall boom including the British revival may ultimately trace back to the Únětice collapse, which opened new opportunities with new trading partners (see S1 Fig). Besides, much copper kept arriving, not only from maintaining well-established contacts in Slovakia, but now also from Mitterberg in the eastern Alps (Fig 14). Despite the three main provenances visible in isotopic and trace-component data, almost all of this copper is now of low-impurity quality. In the light of the previous wide panoply of coppers, this uniformity is remarkable. This low-impurity As = Ni “chalcopyrite” copper must have had qualities much in demand among many communities. It fits the picture of growing standardisation of the metals enterprise across the board, from production to trading. The direct Scandinavian access to the Carpathian basin and the Transdanubian plains that was opened up by the Únětice collapse c. 1600 BC [46] increased in importance in the sixteenth century BC as signs of contact appear with tell settlements in the Koszider period (≈Fårdrup-Hajdúsámson-Sögel metalwork) and the earliest Middle Danube tumulus groups in Bronze Age B1 (≈Valsømagle metalwork). What we see here may be the consolidation of the eastern route, the extension of which now went as far as the Aegean, where Baltic amber was included in the extraordinary shaft grave assemblages of Mycenae [143–146]. Halfway between southern Scandinavia and the Carpathian–Transdanubian crossroads, the Nebra hoard, with its twin sets of Hajdúsámson-derived weaponry made of Mitterberg copper and perhaps even tin from Cornwall [40,41], marks the place where the eastern route branched in two. One of these branches was a westerly itinerary along the River Elbe to the Sögel-Wohlde region of north-west Europe, while a north-easterly and similarly riverine itinerary headed towards the Baltic Sea, crossing over to the Danish isles and Scania. In Scandinavia, these changes concurred with formation of a new social order, identified by an emblematic style among prominent warriors in the incipient NBA. This period saw the first rush of construction of large burial mounds [122,123], erected as monuments to commemorate individual founders of this warrior class who carried Valsømagle-type gear. Crucially in NBA IB, Italian AATV copper is faintly discernible among the copper provenances in the Bronze Age dataset. This development signals the onset of changes that came to full fruition after c. 1500–1450 BC. In NBA II (1500–1300 BC), British copper is no longer detectable in the dataset. This may mean that the sea-based trade between southern Scandinavia and the British Isles had declined or ceased and that Italian AATV copper had seized dominance (see S1 Fig), which is in accordance with established knowledge [7,8]. This takeover coincided with establishment of the full-grown NBA, with burial mounds by the thousand and a unifying metalwork style that branded the upper social echelon of men and women in distinct yet shared ways. This tie-up with a prevailingly western riverine and land-based route now connected the NBA region with the South German Tumulus culture and the first transalpine amber traffic. Abundant finds of Baltic amber in the rich mound burials of the South German Tumulus region [147] indicate a major shift in alliances and trading routes. Material culture wise, there are several similarities between the classic NBA II and the South German Tumulus group e.g. [5,50]. Baltic amber was now travelling across the Alps and likely passed through Val Camonica to the Po valley, continuing from there to Apulian coastal entrepots like Roca Vecchia [119,148,149] in South Italy. The three-track approach adopted in this study allows us to draw on the trace elemental and isotopic data diagnostically in conjunction with our detailed classificatory knowledge [based on 4,47,50,52,118,150–171] of the sampled artefacts. None of these methods alone would be capable of revealing the provenance of the metals used for crafting the first sizeable quantity of objects at the turn of the Neolithic to Bronze Age, and further into the first three hundred years of the remarkable Nordic Bronze Age. The study is exploratory, but its structured framework incorporating time, geography and technology, past and present, thus deploying advances both in archaeology and in science has been extremely productive. The inquiry has fulfilled its primary aim: namely, to unveil these ore sources and trading networks that enabled the rise and establishment of the Nordic Bronze Age. Importantly, it has demonstrated that the Nordic Bronze Age was founded on metals from shifting ore sources, in tight correlation with altered trading routes and altered geopolitical and societal setups. The sequence of distinct sociocultural transformations from 2100 to 2000 BC (the turn of LN I to LN II), 1600 BC (the turn of NBA IA to NBA IB) and 1500 BC (the turn to NBA II) has been found to correlate with significant changes in the provenance and class of copper arriving in southern Scandinavia. Supporting information Simplified map of the shifting copper trade routes to southern Scandinavia from 2000 BC -1300 BC.
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