Thailand there lived in Central Thailand or the Menam Basin, in or about the 5th to the 7th century A.D., a people probably akin to the Mons of Lower Burma. They are known archaeologically by the name of their kingdom, in Central Thailand subsequently in the 12th century A.D. became part of the Khmer Empire and later on in the 13th century A.D. passed from the rule of the now decaying Khmer Empire to that of the Thai of Sukhodaya which finally became the nucleus of the present Thai kingdom. Further south, in which is now Central Thailand in the Menam valley or Chao Phya Basin, there were evidently some settlements of the Thai people. At first they were minority groups, which probably late on, formed themselves into semi -independent principalities under the dominant rule of the Khmer Empire in about the 12th century A.D. The Thai of Center Thailand are named Thai-Noi. In recounting the early history of the Thai of Thailand, we deal with the common history of all Thai-speaking people to an identical extent as with the history of Laos and Shans in particular. Some authorities believe that the Thai's first historical appearance was in China some three thousand years ago. Evidence of a kingdom known to the Chinese as Nan-chao meaning lord. Before the kingdom of Nan-chao came into being , the Thai people in Southern China evidently in more or less independent groups . Nan-Chao kingdom was a comparatively powerful state with a high level of culture. It lasted for some seven centuries until it fell in 1253 A.D. "A history of South -East Asia" says that the Thai never ceased to be on the move. (from the earlier days of Nan-Chao) Confining ourselves to the history of the Thai of Thailand, some tribes of the Thai migrated at different times and from different directions into present Thailand a thousand or more years ago.