Thai people most likely originally come from the province of Guangxi in China. Tai peoples began to move south some time between the 8th and 10th centuries. They settled in the valley of the Chao Phraya River. They became heavily influenced by Mon and Khmer and became Buddhist. Early Thai states included the Sukhothai Kingdom and Suphan Buri Province. The Thai were called "Siam" by the Khmer, and were ruled by the Khmer Empire. The Thai people began growing in power after they built Ayutthaya.