Slab Grave expansion disrupted long co-existence of distinct Bronze Age herders in central Mongolia

Dairy pastoralism reached Mongolia in the Early Bronze Age (EBA) with migrating herders and flourished in the Late Bronze Age (LBA) among culturally diverse groups associated with the Deer Stone-Khirigsuur Complex (DSKC) and figure-shaped/Ulaanzuukh burials. While the spread of pastoralism has been widely studied, interactions between culturally distinct pastoralist groups remain underexplored, largely due to challenges in obtaining both genomic and cultural data. In this study, we analyzed genome-wide and cultural data from 30 ancient individuals in central Mongolia, a key region where pastoralist groups with varying mortuary practices converged. We observe an enduring presence of two distinct genetic clusters during LBA, corresponding to DSKC and figure-shaped burials, suggesting limited mixing and a maintenance of cultural distinctions despite their coexistence. These genetic and cultural profiles were eventually replaced during the Early Iron Age by the expansion of a population associated with the emerging slab grave burial tradition. Finally, we refine the genetic origin of the LBA DSKC populations, tracing their minor western Eurasian ancestry back to the Eneolithic/EBA Afanasievo and Khemtseg (Chemurchek) populations. This study provides a fine-scaled genetic tracking of major transitions in prehistoric Mongolia, offering new insights into the complex and divergent processes that shaped ancient pastoralist societies.