starting of the 2 century B.C. the Thai people,original homeland was in the valleys between the Huang Ho and the Yangtze Kiang in China, began to migrate southwards. they became separated into two main groups. One group go and settled in the plains of the Salween River Shan States and other areas and spread on as far as Assam. This group of Thais is called Thai Yai (Big Thai) and the latter group of Thais is called Thai Noi (Small Thai).