From the 3rd to the 14th century there was southward migration of ethnic T’ai (also known as Siam or Thai) from southern district of China called Nan Chau. At the beginning of 13th century, there were the establishments of some small kingdoms in the northern regions of the Khmer Empire. In 1279, the Sukhotei Kingdom was established and later on became Thailand. In 1353, at the northeast, Lan Xang Kingdom (Laos) was founded. Beyond the far northeast region of the Khmer Empire at the Chinese border, there was an establishment of a new state called Chao Chili by the Ytieh (Vietnam). Until the early 900’s, the state of Chao Chili was a vassal state of the Chinese Empire. After the formations of states and regaining independence, the wars began to take a toll on the Khmer Empire. The Thai moved south from the Sokhotei; the Chams and the Vietnamese from the northeast; causing the Khmer Empire to become very weak. Consequently, their territory became smaller and smaller as time went by. The last episode of this tragedy took place when Kampuchea Krom was incorporated into Vietnam rather than Cambodia in 1954.
