Reconstructing the genetic admixture history of Tai‐Kadai and Sinitic people: Insights from genome‐wide SNP data from South China

South China (SC) was a region with mixed rice-millet farming during the Middle Neolithic period and was also suggested to be the homeland of Tai-Kadai (TK)-speaking people. However, the formations of inland TK-speaking people and southwestern Hans are far from clear due to very few studies on this subject. Here, we reveal the spatiotemporally demographic history of SC by analyzing newly-generated genome-wide SNP data of 115 modern southwestern individuals and find that inland TK-speaking Dongs and Bouyeis have a close genomic affinity to coastal TK/Austronesian (AN)-speaking people and Neolithic Yangtze River basin (YZRB) farmers, while southwestern Hans and TK-speaking Gelaos possess a close genomic affinity to Neolithic Yellow River basin (YRB) farmers. Genetic differentiations are identified among TK people from SC and Southeast Asia, and between northern and southern inland Chinese TK people, in which the identified shared genetic ancestry between TK and AN people highlights a common origin of AN/TK groups. Conclusively, our findings indicate that millet farmers deriving from the YRB and rice farmers deriving from the YZRB substantially contribute to the present-day inland TK speakers and southwestern Hans via a two-way admixture scenario of bi-directional gene-flow events, which facilitates the formation of a modern two-way genetic admixture profile.