There arose in the earlier part of the 13th century A.D. two chief of the Thai-Noi who wrested from the Khmers the area of Central Thailand and one of them became the first Thai King of Sukhodaya, a town some 250 kilometers as the crow-flies northward from Bangkok. Under the reign of its third king. Ram Khan hang the Great, a contemporary and friend of the aforesaid Thai King Nengrai of Northern Thailand, the Kingdom of Sukhidaya became a relatively large empire stretching southward through the length of the Malay Peninsula which was the last remnant of the once Javanese Sumatran Empire of Sri Vijaya. Northward, the Sukhodaya Empire touched that of Northern Thailand where reigned, as already mentioned King Mengrai. Eastward but in northerly direction, thought what is now the North-East Area of Thailand which was at that time partly under the spheres of influence of the now decaying Khmer Empire and of the Lao kingdom, the Sukhdaya Empire of King Ram kamhang reached further beyond the river Mekong. Westward it included a part of the Mon country of what is now Lower Burma. Ram Khamhang's outstanding achievements to the present day are his invention of the Thai alphabet in 1283 A.D. ,and the adoption of Buddhism of they Ceylonese's Sect which has remained to this day. He also introduced the manufacturer of glazed pottery by importing artisans, no doubt from China.
In 1350 A.D. there arose a new Thai power in the south of Sukhodaya proper, Ramadhibodi I, known vulgarly as King U-Thong, the first King of Ayudhya.
Northern Thailand where King Mengrai reigned as its first king in the 13th century A.D. but later on in the latter part of the 16th century A.D. It became a part of the Burmese Empire for some two centuries.
Thailand, with Ayudhya as its capital and its succession of kings both weak and strong,endured for 417 years and came to an end in 1767 A.D. through a war with Burma. did Thailand pass from her medieval period and enter a new phase of progressive revolution following the Western trend which is a matter of modern history.