Proceedings of the National Academy of Sciences of the United States of America
Along with numerous researchers such as Valentin Thouzeau, Robin J. Ryder, Simon J. Greenhill, Johann-Mattis List, Guillaume Jacques and Yunfan Lai, Sagart conclude in a study published in the "Proceedings of the National Academy of Sciences of the United States of America" that the Sino-Tibetan languages originated among millet farmers, located in North China, around 7,200 years ago.