Sukhothai

a medieval Thai state named for the city of Sukhothai, which was its capital. The Sukhothai state was founded in the early 13th century by the Thai leader Phra Ruang, who ruled as Pho Kun (King) Sri Indraditya. It reached its peak of development under King Rama Kamkhaeng (Rama the Great), who ruled from 1275 to approximately 1317. During his reign, the boundaries of Sukhothai extended westward to the Andaman Sea and southward to the Malay Peninsula. The ancient culture of the Mon-Khmer peoples in the south of the country played a significant role in Sukhothai. For example, in 1283 the Khmer alphabet served as a basis for the first Thai alphabet.

The vast state had weak economic ties and disintegrated soon after the death of Rama Kamkhaeng. By 1378, Sukhothai had dwindled to the size of a small principality and recognized its vassalage to the kingdom of Ayutthaya, which seized it in 1438.