A third theory propounds that the Thais were originally of Austronesian, rather than Mongoloid, stock and had migrated northwards from the Malay Archipelago. The most convincing theory, however, is that which relies largely on linguistic evidence. From research done in the southern Chinese provinces of Kwangtung, Kwangsi, and Yunnan, where the Thai language is still spoken, the proponents of this theory maintain that the Thais migrated southward from these provinces.