A genetic history of the Balkans from Roman frontier to Slavic migrations

The rise and fall of the Roman Empire was a socio-political process with enormous ramifications for humanhistory. The Middle Danube was a crucial frontier and a crossroads for population and cultural movement.Here, we present genome-wide data from 136 Balkan individuals dated to the 1st millennium CE. Despiteextensive militarization and cultural influence, we find little ancestry contribution from peoples of Italicdescent. However, we trace a large-scale influx of people of Anatolian ancestry during the Imperial period.Between 250 and 550 CE, we detect migrants with ancestry from Central/Northern Europe and the Steppe,confirming that ‘‘barbarian’’ migrations were propelled by ethnically diverse confederations. Following theend of Roman control, we detect the large-scale arrival of individuals who were genetically similar to modernEastern European Slavic-speaking populations, who contributed 30%–60% of the ancestry of Balkan people,representing one of the largest permanent demographic changes anywhere in Europe during the MigrationPeriod.