One theory is that the Thai race immigrated southwards into Southeast Asia from the Altai mountain range in northwestern China-Mongolia. Since archaeological, ethnographic, and linguistic researches do not bear this out, the theory now has few champions. Another unconvincing hypothesis contends that the Thai, having migrated from Sichuan province in central China, founded a kingdom in southern China called Nanchao, from whence they were driven further south by the all-conquering Mongol ruler Kubilai (Kublai Khan) in 1253, into Indochina and present-day Thailand. This theory is not very tenable because Nanchao was not a Thai-dominated kingdom, and it appears too that Thai had immigrated into the area that is now Thailand well before 1253.