From Sukhothai, which has greatly prospered in the reign of King Ramkhamhaeng and Phya Lithai. But after that, It began to change because of the invasion of Ayutthaya. This is a city that has developed and expanded its territory greatly in that time fitted. Until it can seize the land of Sukhothai. Sukhothai was annexed into the territory of the Kingdom of Ayutthaya
Ayutthaya was officially established since 1893 by King U-Thong. Ayutthaya kingdom that established this nation is considered as the center of Thailand in the Mekong river. But it is not the nature of the nation state.