Comparative linguistic research seems to indicate that the Tai people were a proto Tai-Kadai speaking culture of southern China, and that they, like the Malay-Polynesians, may have originally been of Austronesian descent. Prior to inhabiting mainland China, the Tai are suspected to have migrated from a homeland on the island of Taiwan where they spoke a dialect of Proto-Austronesian or one of its descendant languages. After the arrival of Sino-Tibetan speaking ethnic groups from mainland China to the island of Taiwan, the Tai would have then migrated into mainland China, perhaps along the Pearl River, where their language greatly changed in character from the other Austonesian languages under influence of Sino-Tibetan and Hmong-Mien language infusion. The coming of the Han Chinese to this region of southern China may have prompted the Tai to migrate in mass once again, this time southward over the mountains of southern China into Southeast Asia via the mountains of Burma and Laos to the north of Thailand. It is believed that the Tai ethnic groups began migrating southward from China and into Southeast Asia during the first millennium A.D. While this theory of the origin of the Tai is currently the leading theory, there is insufficient archaeological evidence to prove or disprove the proposition at this time, and the linguistic evidence alone is not conclusive. However, in further support of the theory, it is believed that the O1 Y-DNA haplogroup is associated with both the Austronesian people and the Tai.
