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 or Minor Thai in contradistinction to the Shans of Upper Burma who are named Tai Long or Thai-Yai i.e. Major Thai. it is a traditional belief that the Thai-Noi or Minor Thai of central Thailand came from the Thai of Northern Thailand and the Lao kingdom. This may be so but on the other hand there are indications that the Shans of Upper Burma might have had a share, if not much, in making up the ingredients of the Thai-Noi too.