Ancient genomes reveal a rare maternal lineage of domestic horse in China

Domestic horses had a significant impact on the development of ancient Chinese society, but their maternal lineages remain unclear. Our study analyzed the complete mitochondrial genome of 16 ancient horses from the Baiyanghe tombs in Xinjiang, dating from 700 cal BC to 900 CE. The study found that Northwest China has a long history of horse breeding, which is attributed to the natural environment suitable for animal husbandry and constant exchange with surrounding populations and cultures. A sample belonging to the rare maternal haplogroup E was surprisingly uncovered at the site. This group underwent two population expansion events and was first discovered in the Xinjiang region of China during the middle of the first millennium. These results provide new evidence for the high mitochondrial diversity of horses observed throughout Eurasia including China, and that the mitochondrial DNA is not geographically informative in horses.