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Post by Admin on Mar 2, 2022 19:00:06 GMT
Population continuity within the Indo-Iranians To formally test for genetic continuity with Iron Age southern Central Asia and the limited admixture with Baikal-related populations at the source of the present-day Indo-Iranian speaking populations, we performed D-statistics, f3-statistics and qpAdm modelling on the same dataset used for the PCA et ADMIXTURE analyses as well as on a dataset formed by shotgun sequences from 3 Yaghnobis (TJY), 19 Tajiks (TJE) and 24 Turkmens (TUR)48 as well as the ancient genomes for a final set of ~ 700k SNPs. We identified and characterized gene flows that occurred since the Iron Age by computing D-statistics of the form D(Mbuti, Ancient population ; Turkmenistan_IA, present day Indo-Iranian) for every ancient population in our dataset (Fig. 3, Table S5). These statistics are expected positive when gene flows occurred from the Ancient population to the present-day Indo-Iranians. For the Yaghnobis, only one individual, an Iron Age individual from Nepal genetically close to East Asian populations (Nepal_Chokhopani_2700BP.SG)45, has a significantly positive D-statistic (Z > 3). Tajik individuals (TJE) display a higher number of ancient populations (N = 41) for which D-statistic is positive; the common characteristic of these ancient populations is to exhibit a large amount of BHG ancestry, consistently with the ADMIXTURE analysis (Fig. 2). We also note that the Tajiks present a positive D-statistic with an historical individual from India (Great Andaman) (Fig. 3) showing a possible connection with South Asia. Thus, modern Indo-Iranian populations descend from groups related to those present in Turkmenistan as early as Iron Age, with a contribution from another East Asian population who brought the BHG ancestry and, except for Yaghnobis, a contribution from a South Asian population. Figure 3 Then, we formally test if the contributions detected with D-statistics are due to admixture events that occurred since the Iron Age. We first computed f3-statistic49 of the form f3(TJY/TJA/TJE/TAB ; Source1, Source2), that is expected to be negative (Z < -3) if the Indo-Iranian populations can be modeled as admixed between the two sources (Table S7). Only combinations implying a population from East Asia ancestry (like the XiongNu) and westerner populations representing the components seen in the ADMIXTURE analysis (Iranian Neolithic, Anatolian farmer, and Steppe ancestry) were significant (Fig. 2). These statistics attest to the existence of an actual admixture between a population probably presenting a mix of Iran Neolithic, BMAC, Anatolian early neolithic and Bronze Age Steppe ancestry with a population with a strong affinity to the BHG ancestry. The Yaghnobi population has significantly fewer pairs with a negative f3-statistic than the Tajik populations, probably due to their long-term isolation. We also specifically calculated f3-statistic of the form f3(TJY/TJA/TJE/TAB; Ancient population, Turkmenistan_IA) and obtained several negative f3-statistics always with the same ancient populations implied in the positive D-statistic (see Supplementary fig. S3, Table S6) showing that Indo-Iranians can be successfully modelled as the admixture of Iron Age Turkmenistan and BHG-related population. We then modelled Yaghnobi and Tajik populations using qpAdm23 to estimate mixture proportions. To test which proximal populations fit the best in our model, we used the rotating method23 and we excluded all combinations with a p-value ≤ 0.01. We first tried a two-ways admixture testing several possibilities among rotating sources. For the Yaghnobis, the only model retained was the one with ~ 93–88% from Turkmenistan_IA and ~ 7–12% ancestry from XiongNu (Table 1). With 3-ways modelling, we could not reject different models for TJY: 3 models imply 90% ancestry from Turkmenistan_IA and 7% ancestry from XiongNu, and around 3% of ancestry from Europe_EN, BMAC or Ukraine_Scythian; we also obtained a model with Ukraine_Scythian, BMAC and XiongNu inferring the older admixture at the origin of Turkmenistan_IA (Table 1). When testing for more admixture sources, we obtained only two 4-ways models and one 5-ways model (Supp. Data). One interesting model is a 4-ways model with 17% Ukrainian Scythians, 60% Turkmenistan_IA, 14% BMAC and 8% XiongNu, i.e. this model shows a close affinity of Yaghnobis with Western Steppe-like populations. To model Tajiks, all 2-ways admixture models were excluded and we obtained one 3-ways admixture model (p-value = 0.49) implying around 17% ancestry from XiongNu, almost 75% ancestry from Turkmenistan_IA, and around 8% ancestry from a South Asian individual (Indian_GreatAndaman_100BP)50 representing a deep ancestry in South Asia (Table 1). Target Source left populations p-value Admixture proportion SE A B C A B C A B C TJY TurkmenIA XiongNu 0.2462 0.933 0.067 0.010 0.010 TJY TurkmenIA XiongNu EuropeEN 0.2691 0.897 0.071 0.032 0,044 0.010 0.041 TJY TurkmenIA XiongNu BMAC 0.1301 0.906 0.068 0.026 0.104 0.011 0.107 TJY TurkmenIA XiongNu UkraineScythian 0.0911 0.899 0.069 0.032 0.052 0.010 0.048 TJA TurkmenIA XiongNu GreatAndaman_100BP 0.2780 0.709 0.165 0.129 0.053 0.022 0.072 TUR TAB GoldenHorde 0.48007 0.941 0.059 0.005 0.005 TurkIA BMAC Andronovo 0.327016 0.471 0.529 Thus, the qpAdm modelling shows that at least 90% of the ancestry of current Indo-Iranian ancestry is modelized as inherited from Iron Age individuals from southern Central Asia with an affinity with BMAC. Consequently, Indo-Iranians present a strong genetic continuity in the region since the Iron Age with anecdotic admixture with BHG ancestry related individuals, and, for the Tajiks, with South Asian ancestry related populations possibly after Iron Age. Finally, we used DATES18 to estimate the number of generations since the admixture events. We obtained 35 ± 15 generations for the admixture between Turkmenistan_IA and XiongNu-like populations at the origins of the Yaghnobis, i.e. an admixture event dating back to ~ 1019 ± 447 years ago considering 29 years per generation51. For Tajiks (TJE, TAB, TJA) we obtained dates from ~ 546 ± 138 years ago (18.8 ± 4.7 generations) to ~ 907 ± 617 years ago (31.2 ± 21.3 generations) for the West/East admixture. We also obtained a date of ~ 944 ± 300 years ago for the admixture with the South Asian population.
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Post by Admin on Mar 3, 2022 1:09:25 GMT
Iron age Turkmenistan ancestry Previous studies13,18 have already shown Turkmenistan_IA can be modelled as an admixture between BMAC and some steppe populations, and on the PCA (Fig. 1c), Turkmenistan_IA indeed belongs to the steppe cline. However, the steppes are split between several groups (Western steppe, Central steppe, Eastern steppe) depending on their amount of Eastern Asian ancestry. The ADMIXTURE analysis discriminates the Western and Central steppe ancestries by the presence of a red and mauve component (maximized respectively in East-Siberia and East Asia populations) in the latter, which is absent from Turkmenistan_IA, indicating an affinity with the Western steppe. Nevertheless, we noted that Andronovo or Sintashta individuals also lacked this component while being classified as Central_Steppe. Thus Central_Steppe group is highly heterogenous and gathers populations with some East-Asian ancestry like Karasuk or Central Saka and others more Western steppe-like as Andronovo and Sintashta. Furthermore, we obtained the higher f3-outgroup statistic of the form f3(Mbuti; Ancient pop, Turkmenistan_IA) for ancient populations from BMAC complex or West Eurasia, highlighting the double origin and affinity with the West. This affinity is further confirmed with D-statistics of form D(Mbuti, Turkmenistan_IA; Western_Steppe, Central_Steppe) (Fig. 4B) that are significantly negative (Z < -3) when a Western_Steppe population is opposed to a Central_Steppe population with an East Asian ancestry, like Central Saka or Karasuk (Fig. 4B). With D-statistic of the form D(Mbuti, Turkmenistan_IA; HG1 , HG2) – HG1 and HG2 belonging to WEHG, EEHG, WSHG, and BHG populations – we evidenced that the steppe populations admixed with BMAC lacked East Asian or Baikal component (Fig. 4A). Indeed, we only see significant D-statistics when BHG was confronted with the other HGs (Fig. 4A). Using HG populations avoids inferences from recent admixture; nevertheless, it failed to discriminate between most of the different steppe groups of this period at this level. This suggests that Turkmenistan_IA is devoid of the East Asian ancestry observed in several Central steppe groups as early as Bronze Age. Figure 4 Finally, we tested different steppe populations which admixed with BMAC to model Turkmenistan_IA with qpAdm. We first constituted a set with Poltavka, Srubnaya (Western_Steppe) and 4 individuals from Russia labelled as Andronovo (Central_Steppe)52, to estimate the affinity with Europe and Western steppe previously highlighted with D-statistics and f3-statistics. We only obtained one model with 2 sources that we could not exclude (Table 1), and it implies an admixture of 43% BMAC and 57% Andronovo (p-value = 0.31) suggesting that Andronovo individuals are the best proxy for the steppe population which admixed with BMAC to form the Iron Age southern Central Asia group. When testing for the best model between Andronovo and Karasuk (Central steppe with East Asian component) to estimate the affinity with Asia, we produced a single fitting/ relevant model implying Andronovo (p-value = 0.51) with roughly the same proportions. Further tests explored the best model between Andronovo and Sintashta, two genetically close populations, and the single significantly outcome was the one with Andronovo and BMAC (p-value = 0.498) in the same proportions. Eventually, we tested the best model between the individuals labelled Andronovo and two populations belonging to the Andronovo-complex: Fedorovo Shoindykol18 and Alakul Lisakovskiy18. Once again, the only valid model was the one with Andronovo and BMAC. Overall, we can say that the Iron Age population from southern Central Asia emerges from the admixture of BMAC with a Bronze Age population close to the Andronovo individuals, which presents a profile with an affinity with Western steppe rather than with a Central steppe with an affinity with East Asia (like Karasuk).
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Post by Admin on Mar 3, 2022 22:08:23 GMT
A Turkmens’ history Despite speaking a Turko-Mongol language and having the same cultural practices as other Turko-Mongol ethnic groups53, Turkmens are genetically closer to Indo-Iranian populations than to Turko-Mongols54,55. Indeed, Turkmens (TUR) fall into the Tajiks cluster and not in the Turko-Mongol cline in the PCA (Fig. 1) and in the ADMIXTURE analysis (Fig. 2), all Turko-Mongol populations from Central Asia except Turkmens show a significant (t-test, p-value < 2.10–16) high amount of Baikal (red component, mean 50%) and East Asian ancestry (pink component, maximized in the Han population). Turkmens, for their part, display a completely different pattern, with an amount of Baikal component (mean value: 22%) closer to the proportion in Tajiks (mean value: 15%) and almost no East Asian component. They do not show as much South Asia related ancestry as Tajiks, suggesting that the admixture with South Asian populations occurred or continued after Turkmens split from the remainder of the Indo-Iranian group. We have established genetic affinity profiles with ancient populations for all Central Asia populations including Turkmens of the first dataset, based on f3-outgroup statistics of the form f3(Mbuti; Ancient pop, Present-day pop) (Fig. 5; Table S8). The f3-outgroup values comparing Turkmen to any ancient population are strongly correlated with the one comparing Tajiks to any ancient populations (Fig. 5a). On the other hand, f3-outgroups values comparing Eastern steppes and Baikal groups to a Turko-Mongol population (Kazakhs) are higher than those comparing these ancient populations to Turkmens (Fig. 5b). The Turkmens are more similar to Indo-Iranian populations than to any Turko-Mongol population on the amount of shared Siberian/East Asian ancestry. Turkmens’ affinity with Tajiks rather than with Turko-Mongol groups shown by f3 statistics of the form f3(Mbuti; TUR/TJA/AKZ , Ancient population). (A) Outgroup f3-statistics for Turkmen and for Tajiks (TJA) plotted against each other. (B) Outgroup f3-statistics for Turkmen and for Kazakhs (AKZ), belonging to the Turko-Mongol group, plotted against each other. (Figure done with ggplot2 v. 3.3.3 R package cran.r-project.org/web/packages/ggplot2/index.html). Finally, we modeled Turkmens as a mixture of Central Asia basal ancestry (represented by Yaghnobis) and East Asian ancestry (we obtained a negative value for f3(TUR; TJY, DevilsCave_N); f3 = −0.0025, Z = −5.266). qpAdm modelling for Turkmens produces a single nonrejected model (p-value = 0.048007) implying 6% of Golden Horde Asian and 94% of Tajiks (TAB) (with TJY, XiongNu, GoldenHordeAsian, TAB, Turkmenistan_IA as potential rotating left population) (Table 1). For this admixture event, we estimated a date of 687 ± 100 BP (23.7 ± generations) with DATES. These results enlighten that Turkmens were an Indo-Iranian-like population not so long ago, who recently shifted language and culture without a substantial genetic change in population.
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Post by Admin on Mar 4, 2022 1:15:44 GMT
Discussion Our research provides insight into the history of Indo-Iranians by using evidence to trace modern populations back to the Iron Age in southern Central Asia. As proposed by former genetic studies2,11 and as supported by historical56 and archaeological evidence57, we found that Indo-Iranian speakers settled in Central Asia long before Turko-Mongol speakers11. The main event at the bottom of Indo-Iranian ancestry in southern Central Asia occurred at the end of the Bronze Age/Early Iron Age, through the admixture between local BMAC groups and Andronovo-related populations perhaps linked to the end of the Oxus Civilization. We note here that the steppe group who admixed with BMAC did not present East Asian ancestry, which is consistent with both the archeological58 and genetic38 findings of the East Asian ancestry arriving in the Central steppe core only at the end of the Iron Age.
The populations falling under the name Andronovo form a complex group. Indeed, when screening the individuals used under the label Andronovo in our dataset, we note that they all belong to one site, Kytmanovo52,59, which is eastward, but show a genetic profile very close to the Sintashta individuals, whose area expanded near the Caspian Sea. Individuals from other cultures belonging to the Andronovo complex have been sequenced17,18 but overall they form a moderately heterogenous genetic group. Moreover, some studies have shown that Steppe groups can be labelled similarly but be different genetically, such as, for instance, Srubnaya Alakulskaya individuals being closer to Andronovo individuals than to Srubnaya from the Samara region28. The nomadic populations from the end of the Bronze and Iron Age being very genetically heterogenous, we suspect that the source of the Western steppe ancestry found in Iron Age southern Central Asia may not be sampled yet. It is interesting to notice that the gene flow between the Steppe and southern Central Asia went two-ways38,60. A recent study60 has highlighted that a gene flow from BMAC contributed to the genetic formation of Scythians. Our findings combined with these studies strongly corroborate the hypothesis based on archaeological evidence that southern Central Asia civilizations since BMAC and Western steppe culture had a strong cultural connection6,8,61,62,63,64.
Overall, we demonstrate here a remarkable example of genetic continuity since the Iron Age in Indo-Iranian populations from Central Asia despite the frenzy of population migrations in the area since the Bronze Age. Similar to Zhabagin et al. work65, the present study shows no impact of the Arab cultural expansion in Central Asia on the Indo-Iranian speaker’s genetic diversity, despite the first one leading to a shift in language for Tajiks. We also do not see a gene flow from Iran despite the Persian cultural expansion which led to a language shift from an east-Iranian language to a west-Iranian in Tajiks—when Yaghnobis kept their east-Iranian language66.
Yaghnobis, for their pair, are characterized by strong genetic stability over time (small amount of negative admixture f3-statistics, fewer significative D-statistics), which can be linked back to their long-term isolation12,67. Yaghnobis are indeed an isolated ethno-linguistic population historically present in the hardly accessible valley of the Yaghnob River. Evidence suggests that the separation between Yaghnobis and Tajiks occurred at least 1000 years ago, which explains the high genetic differentiation observed in Indo-Iranians by previous studies53,67. Interestingly, it implies that Yaghnobis could represent a good proxy for the ancestry present in Central Asia before the migration waves that led to the current genetic diversity, despite the strong drift that occurred.
The amount of East-Asian ancestry due to admixture with modern Turko-Mongol groups remains low even in Tajiks, consistent with the findings of Martinez-Cruz et al.2, who observed the light impact the westward invasions (Huns, Mongols) had on Indo-Iranian groups in Central Asia. On the other hand, we have highlighted for Yaghnobis, Tajiks, and Turkmens a small amount of gene flow from BHG-ancestry dating to around 1000 years ago, suggesting a recent wave of westward migration from the Altai mountains, after the Iron Age. This recent wave can be linked to the origin of the Turko-Mongol in Central Asia which has been demonstrated by Martinez-Cruz et al.2 and Li et al.68 to be from an ancestral group of Turkic speakers from the Altai region. Our quite recent date of admixture differs significantly from the date obtained by Palstra et al.11 which placed the admixture event back to 8 ky BP for Tajiks and 2.3 ky BP for Kyrgyz. The more recent inferred dates of admixture for Tajiks compared to Yaghnobis could be explained by the fact that Tajiks received a more continuous gene flow from the eastward source, continuous gene flow that occurred after the first admixture event that formed the Yaghnobis genetic composition. Indeed, the qpAdm method cannot detect a continuous admixture which can be expected in this context. Furthermore, the search of their ancestry confirms a genetic homogeneity within Yaghnobis, Tajiks, and Turkmens, despite their cultural, notably linguistic differences, with some genetic differences emerging from various patterns of gene flow in Tajiks and Turkmens.
Notably, we evidenced an admixture event from South Asia restricted to the Tajik population, undocumented before despite evidence in Iranian Turkmens69. According to previous archaeological studies70,71, multidirectional cultural exchanges with South Asia are known to have taken place as early as the Chalcolithic period: notably from Sialk culture and other Iranian cultures towards Balochistan70 or from Geoksjur culture of Turkmenistan to southern Afghanistan. In the opposite direction, from south to north, Mundigak III type ceramics find parallels as far as Badakhshan in northeast Afghanistan, material from Balochistan and shells used in necklaces and bracelets from the Arabian Sea are found at the Sarazm site in Tajikistan, showing a long-distance commercial exchange. All these ancient populations were on the move with probably quite frequent exchanges and cultural blends between populations, Iron Age included71. Intriguingly, genetic proximity between southern Central Asian and South Asian groups has already been suggested for BMAC samples18 and raises the question of the timing of this gene flow. Two models can be considered: the first one assumes the formation of a homogeneous basal Indo-Iranian background (as observed today in Yaghnobis) and subsequent recent gene flow from South Asian populations; the second model acknowledges the presence of South Asian ancestry in some Bronze Age BMAC samples18 and suggests Tajiks and Yaghnobis could have derived from distinct BMAC populations, respectively with and without South Asian ancestry, who have both experienced independent admixture with Andronovo-like steppe populations during Iron Age, and eastern nomads with BHG ancestry afterwards. Because the date of the gene-flow from South Asian populations in Tajik genomes is relatively recent, the data favours the first hypothesis; however, uncertainties on the model of admixture (one versus several pulses) may be compatible with continuous gene-flow since the Bronze Age. Additionally, our recent date of admixture fits with the arrival of the South Asian ancestry at the same that the shift from east to west-Iranian language in Tajiks linked to the Persian expansion 1500 years ago66.
Lastly, the case of Turkmens is a notable example of a population changing language and cultural practices without substantial changes in their genetic ancestry. Indeed, Turkic-speaking peoples found in all Eurasia are the result of several nomadic migrations14,72, which cover an area ranging from Siberia to Eastern Europe and the Middle East, through Central Asia and have been occurring during a wide period, the 5th–16th centuries14. In regions other than Central Asia, several studies have shown that Turkic-speaking peoples genetically resemble their geographic neighbours, with no clear genetic signal that would distinguish them14,72. This lends to support the model of a language replacement by elite-dominance rather than by demic diffusion for languages of the Turkish family expansion72. Turkmens fit in this global model but are an exception in their region. Indeed, the other Turkic-speaking populations, like Kyrgyz or Kazakhs, show a different genetic profile with a clear dominant East Asian and Baikal components, attesting to a more significant admixture with nomads from South-Siberia and Mongolia, which have been dated around the tenth-fourteenth centuries14. The small amount of East Asian ancestry in Turkmens has been linked to an admixture dated around the 15th century, so slightly after the first admixture in Central Asia, and may come from gene flow with these Turco-Mongol groups.
The question of the diffusion of Indo-European languages has been a hot topic in the last few years23,52,73,74,75. Linguistic analyses point either to Anatolia74 or the Pontic Steppe75 as the region where the Indo-European languages originated. The expansion of Yamnaya related populations westward during the late Neolithic, and eastward during the Bronze Age, through the migration of Andronovo groups, suggests that they were speakers of such languages. Interestingly, the ancestry pattern found in Indo-Iranian speakers from Central Asia is not found in other Indo-Iranian speaking populations, namely, the Iranians Persians69. This ethnic group displays a genetic continuity since the Bronze Age with ancient individuals from Iran, with limited gene flow from the steppes (either Central or Eastern)69. Furthermore, our study of the Turkmen population presents another example where language and genetics do not match, questioning the idea of inferring language displacement using population movement. Their genetic affiliation to modern western Eurasian populations, seen in earlier studies, is due to a common steppe ancestry.
Conclusion Our results bring to light that for Indo-Iranian speakers various patterns of genetic and linguistic continuity or discontinuity coexisted through time. In southern Central Asia, we show that the actual Indo-Iranians are the product of a long-term continuity since the Iron Age with only limited recent impulses from other Eurasian groups. Our results provide further evidence that the demography of this region is complex and needs small-scale studies like this one to be fully understood. From this perspective, the precise timing of these impulses cannot be solved until more genetic data from samples from the Iron Age and historical times, who do not belong to the Steppe cultural complex, have been obtained.
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Post by Admin on Mar 4, 2022 19:55:32 GMT
Genetic Continuity of Bronze Age Ancestry with Increased Steppe-Related Ancestry in Late Iron Age Uzbekistan
Abstract Although Uzbekistan and Central Asia are known for the well-studied Bronze Age civilization of the Bactria–Margiana Archaeological Complex (BMAC), the lesser-known Iron Age was also a dynamic period that resulted in increased interaction and admixture among different cultures from this region. To broaden our understanding of events that impacted the demography and population structure of this region, we generated 27 genome-wide single-nucleotide polymorphism capture data sets of Late Iron Age individuals around the Historical Kushan time period (∼2100–1500 BP) from three sites in South Uzbekistan. Overall, Bronze Age ancestry persists into the Iron Age in Uzbekistan, with no major replacements of populations with Steppe-related ancestry. However, these individuals suggest diverse ancestries related to Iranian farmers, Anatolian farmers, and Steppe herders, with a small amount of West European Hunter Gatherer, East Asian, and South Asian Hunter Gatherer ancestry as well. Genetic affinity toward the Late Bronze Age Steppe herders and a higher Steppe-related ancestry than that found in BMAC populations suggest an increased mobility and interaction of individuals from the Northern Steppe in a Southward direction. In addition, a decrease of Iranian and an increase of Anatolian farmer-like ancestry in Uzbekistan Iron Age individuals were observed compared with the BMAC populations from Uzbekistan. Thus, despite continuity from the Bronze Age, increased admixture played a major role in the shift from the Bronze to the Iron Age in southern Uzbekistan. This mixed ancestry is also observed in other parts of the Steppe and Central Asia, suggesting more widespread admixture among local populations.
Keywords: ancient DNA, population genomics, evolution
Introduction Uzbekistan, in Central Asia, includes diverse populations with both East and West Eurasian ancestries (Irwin et al. 2010). During the Bronze Age (BA), the emergence of pastoral economies led to an increased mobility and the development of many settlements across Central Asia (Kohl 2007; Frachetti 2012; Spengler 2015). Many such pastoral settlements from the Mid-BA (∼2100–1800 BCE), particularly in and around South Uzbekistan, possess a material culture associated with the Bactria–Margiana Archaeological Complex (BMAC) (Kohl 2007; Cunliffe 2015). In particular, BA Uzbekistan populations show similar ancestry profiles to those found in other BMAC settlements around the Amu Dariya River, suggesting interactions and connections between them (Narasimhan et al. 2019). The BMAC populations were previously shown to be primarily a mixture of Iranian (∼60–65%) and Anatolian (∼20–25%) farmer ancestries (Narasimhan et al. 2019). Some BMAC individuals were found to have high Yamnaya/Steppe-related ancestry, suggesting this ancestry began appearing in Central Asia by around ∼4100 BP (Narasimhan et al. 2019). Later, in the Mid and Late BA, communities residing in the Bactrian region of Uzbekistan showed higher Steppe-related ancestry compared with the Early BA populations, suggesting an increased influence from the Steppe herders in Uzbekistan (Narasimhan et al. 2019).
In Central Asia, the transition from the BA to the Iron Age (IA) toward the middle of the second millennium BCE is characterized by major shifts in material culture with increased mobility and interaction (Cunliffe 2015). During the Early IA, South-Central Asia contained many important settlements, such as Bactria, located in the Amu-Darya basin, Margiana, located near the delta of the Murghab River, Sgodia, around the Zeravshan River basin, and Fergana valley, near the Tianshan mountain range (Lhuillier and Mashkour 2017). During the beginning of the IA (∼1500–1400 BCE) a new culture, “Yaz,” appeared in South-Central Asia characterized by a shift in material culture that included a distinct hand-made pottery and different funerary practices, which lacked prominent graves like the Kurgan-style burial graves observed in the Steppe region (Sarmiento and Lhuillier 2011; Lhuillier and Mashkour 2017). Later, during the middle IA, which extended from ∼1000 BCE until the conquest of Central Asia by the Achaemenids, the Persian Empire saw the development of large settlements, advancement in Iron metallurgy technology and with a new wheel-made pottery style by the “Yaz II” culture, followed by the late IA establishment of the Achaemenid Empire (∼550–330 BCE), also sometimes referred to as “Yaz III” (Kuhrt 2001; Wu et al. 2015; Lhuillier and Mashkour 2017).
Later, this region was under the control of the Greco-Bactrian-Kingdom (∼250–125 BCE) (Abazov 2008), during which major upheavals occurred, with migrations and settlements by Indo-European tribes such as the Sakas from North Asia and later by the Yuezhi people from East Asia, who went on to establish the Kushan Empire (∼1st century CE) (Abdullaev 2007; Abazov 2008; Cunliffe 2015; Lhuillier and Mashkour 2017). In general, in archaeological and genetic studies, the impact of Steppe-related culture and ancestry increased from the BA to IA in Central Asia (Cunliffe 2015; Narasimhan et al. 2019), thus genetically, a question remains of how Steppe-related migration into this region from the BA impacted the late IA populations in Central Asia. To address this question, and the general lack of post-BA genomic data from Uzbekistan, we sequenced 27 ancient samples from the Late IA encompassing the Kushan time period (Uz_IA) (∼2100–1500 BP), from three sites in South Uzbekistan: Rabat, Serkharakat, and Dehkan (fig. 1A and supplementary table S1, Supplementary Material online).
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