Bronze and Iron Age genomes reveal the integration of diverse ancestries in the Tarim Basin

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Abstract: The Tarim Basin in Xinjiang functioned as a crucial meeting point for peoples, cultures, and goods across the Eurasian steppe and served as the easternmost edge for western steppe population dispersal Despite its importance as a historical crossroads, the prehistoric genetic history of the region remains largely unexamined, which results in a major gap in understanding Eurasian population movements and steppe group expansion to the east. Here, we present genome-wide data from 24 individuals from the western Tarim Basin during the Bronze and Iron Ages. Our findings reveal that Bronze Age populations derived most of their ancestry from pastoralist groups, likely tracing back to the rapid eastward expansion of early Andronovo-related cultures in western steppes. As these steppe groups migrated, they first admixed with Bactria-Margiana Archaeological Complex (BMAC)-related agricultural populations and later with indigenous groups represented by the Bronze Age Tarim mummies, ultimately shaping the genetic landscape of the western Tarim Basin. Many of these individuals are genetically distinct from Andronovo-related groups in western Xinjiang,2 indicating that at least two separate waves facilitated the entry of steppe populations into Xinjiang. Notably, we identified an Iron Age individual from western Tarim Basin who appears largely unaffected by the steppe influx, pointing to a previously unrecognized direct genetic admixture between BMAC and the indigenous ancestors of the Tarim. This underscores the genetic heterogeneity of the Iron Age Tarim and suggests that a long-lasting indigenous legacy endured for more than 1,000 years.