Thailand (previously known as Siam) has been populated ever since the dawn of civilization in Asia. There are conflicting opinions of the origins of the Thais. It presumed that about 4,500 years. Thais originated in northwestern Szechuan in China and later migrated down to Thailand along the southern part of China. They split into two main groups. One settled down in the North and became the kingdom of "Lanna" and the other one is in further south, which afterward was defeated by the Khmers and became the kingdom of "Sukhothai".
There are conflicting opinions as to the origins of the Thais. Three decades ago it could be said with presumed certainty that the Thais originated in the southern part of what is now China about 4,500 years ago. Recently, however, this theory has been altered by the discovery of prehistoric artifacts in the village of Ban Chiang in the Nong Han District of UdonThani province in the Northeast. From these evidence of bronze metallurgy going back 3,500 years, as well as other indication of a far more sophisticated culture than any previously suspected by archaeologists. It now appears that the Thais might have originated here in Thailand and later scattered to various parts of Asia, including China.
The controversy over the origin of the Thais shows no sign of definite conclusion as many more theories have been put forward and some even go further to say that Thais were originally of Austronesian rather than Mongoloid. What the outcomes of the dispute may be, by the 13th century the Thais had already settled down within the southeast Asia.