摘要The Han Chinese are the world's largest ethnic group residing across China.Shaanxi province in northern China was a pastoral-agricultural interlacing region sensitive to climate change since Neolithic times,which makes it a vital place for studying population dynamics.However,genetic studies of Shaanxi Han are underrepresented due to the lack of high-density sampling and genome-wide data.Here,we genotyped 700 000 single nucleotide polymorphisms(SNPs)in 200 Han individuals from nine populations in Shaanxi and compared with available modem and ancient Eurasian individuals.We revealed a north-south genetic cline in Han Chinese with Shaanxi Han locating at the northern side of the cline.We detected the western Eurasian-related admixture in Shaanxi populations,especially in Guanzhong and Shanbei Han Chinese in proportions of 2％-4.6％.Shaanxi Han were suggested to derive a large part of ancestry(39％-69％)from a lineage that also contributed largely to ancient and present-day Tibetans(85％)as well as southern Han,supporting the common northern China origin of modem Sino-Tibetan-speaking populations and southwestward expansion of millet farmers from the middle-upper Yellow River Basin to the Tibetan Plateau and to southern China.The rest of the ancestry of Shaanxi Han was from a lineage closely related to ancient and present-day Austronesian and Tai-Kadai speaking populations in southern China and Southeast Asia.We also observed a genetic substructure in Shaanxi Han in terms of north-south-related ancestry corresponding well to the latitudes.Maternal mitochondrial DNA and paternal Y-chromosome lineages further demonstrated the aforementioned admixture pattern of Han Chinese in Shaanxi province.