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Chinese Tajiks are an Indo‐Iranian‐speaking population in Xinjiang, northwest China. Although the complex demographic history has been characterized, the ancestral sources and genetic admixture of Indo‐Iranian‐speaking groups in this region remain poorly understood. We here provide the genome‐wide genotyping data for over 700 000 single‐nucleotide polymorphisms (SNPs) and mtDNA multiplex sequencing data in 64 Chinese male Tajik individuals from two dialect groups, Wakhi and Selekur. We applied principal component analysis (PCA), ADMIXTURE, f‐statistics, treemix, qpWave/qpAdm, Admixture‐induced Linkage Disequilibrium for Evolutionary Relationships (ALDER), and Fst analyses to infer a fine‐scale population genetic structure and admixture history. Our results reveal that Chinese Tajiks showed the closest affinity and similar genetic admixture pattern with ancient Xinjiang populations, especially Xinjiang samples in the historical era. Chinese Tajiks also have gene flow from European and Neolithic Iran farmers‐related populations. We observed a genetic substructure in the two Tajik dialect groups. The Selekur‐speaking group who lived in the county had more gene flow from East Asians than Wakhi‐speaking people who inhabited the village. These results document the population movements contributed to the influx of diverse ancestries in the Xinjiang region. [ABSTRACT FROM AUTHOR]

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 modern 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 modern 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. [ABSTRACT FROM AUTHOR]