Traversing on the ancient Overland Silk Road: Insights from paleogenomics of domestic camels in Xi’an city, China

The ancient Overland Silk Road facilitated not only the exchange of goods but also the dispersal of domesticated animals across continents. However, the genetic history of camels, the vital transportation of this trade network, remains poorly understood due to a scarcity of paleogenomic data. Here, we retrieved complete mitogenomes and low-coverage nuclear genomes from three Camelus remains (dated to ~2,300–2,000, ~900–700, and ~300–0 cal BP) excavated in Xi’an, a major eastern hub of ancient Overland Silk Road. Phylogenetic analyses assigned two individuals to domestic Bactrian camels, and one to an Arabian camel, which represents the first genetically identified Arabian camel bone remain in China. Our findings revealed a lack of phylogeographic structure in maternal lineages, consistent with extensive human-mediated dispersal. Notably, admixture analysis possibly provided direct evidence of ancient interspecific hybridization, detecting approximately 7.3% Arabian ancestry in a ~2,300–2,000-year-old domestic Bactrian camel and 45.1% domestic Bactrian-related ancestry in the ~900–700-year-old Arabian camel. This potential bidirectional gene flow underscored the intentional breeding of hybrid camels for trade caravans. Overall, our findings demonstrated that the ancient Overland Silk Road likely acted as a genetic corridor, shaping the demographic history of domestic camels through recurrent mobility and admixture.