Summary Horse domestication revolutionized warfare and accelerated travel, trade, and the geographic expansion of languages. Here, we present the largest DNA time series for a non-human organism to date, including genome-scale data from 149 ancient animals and 129 ancient genomes (≥1-fold coverage), 87 of which are new. This extensive dataset allows us to assess the modern legacy of past equestrian civilizations. We find that two extinct horse lineages existed during early domestication, one at the far western (Iberia) and the other at the far eastern range (Siberia) of Eurasia. None of these contributed significantly to modern diversity. We show that the influence of Persian-related horse lineages increased following the Islamic conquests in Europe and Asia. Multiple alleles associated with elite-racing, including at the MSTN “speed gene,” only rose in popularity within the last millennium. Finally, the development of modern breeding impacted genetic diversity more dramatically than the previous millennia of human management.

Abstract

Archaeological horse remains from Mongolia's late Bronze Age Deer Stone-Khirigsuur (DSK) culture present some of the oldest direct radiocarbon dates for horses in northeast Asia, hinting at an important link between late Bronze Age social developments and the adoption or innovation of horse transport in the region. However, wide error ranges and imprecision associated with calibrated radiocarbon dates obscure the chronology of early domestic horse use in Mongolia and make it difficult to evaluate the role of processes like environmental change, economic interactions, or technological development in the formation of mobile pastoral societies. Using a large sample of new and published radiocarbon dates, this study presents a Bayesian chronological model for the initiation of domestic horse sacrifice at DSK culture sites in Mongolia. Results reveal the rapid spread of horse ritual over a large portion of the eastern Steppe circa 1200 BCE, concurrent with the first appearance of draught horses in China during the late Shang dynasty. These results suggest that key late Bronze Age cultural transformationsspecifically the adoption of mobile pastoralism and early horseback riding-took place during a period of climate amelioration, and may be linked to the expansion of horses into other areas of East Asia.