A thousand years transect of ancient genomes across the Kazakh Steppe shed new light into the origins and demise of the Iron Age nomad cultures of Central Asia.

The Scythians were a multitude of horse-warrior nomad cultures who dwelled in the Eurasian steppe during the first millennium BCE. Due to lack of first-hand written records, little is known about the origins and relations between the different cultures. To address these questions, we produced genome-wide data for 111 ancient individuals retrieved from 39 archaeological sites from the first millennia BCE and CE across the Central Asian Steppe. We uncovered that major admixture events in the Late Bronze Age formed a genetic substratum from which two main Iron Age gene-pools, centered in the Altai and the Urals, emerged. Their demise was mirrored by major genetic turnovers, associated with the spread of the eastern nomad empires in the first centuries CE along with the expansion of Persian-related civilization from the south. Compared to the high genetic heterogeneity of the past, the homogenization of the present-day Kazakhs gene-pool is striking, likely a result of 400 years of strict exogamous social rules