Thais began to emerge as a dominant force in the region in the 13th century, gradually asserting independence from existing Khmer and Mon kingdoms. Founded by Khun Pha Muang and Khun Bang Klang Thao in 1238, the Kingdom was named by its rulers "the dawn of happiness". The Sukhothai Period is often considered the golden era of Thai history, an ideal Thai state in a land of plenty governed by paternal and benevolent kings, the most famous of whom was King Ramkamhaeng the Great (c.1279-98), who greatly expanded the Kingdom’s borders.
In addition to developing some of the most beautiful Thai art, the Sukhothai Kingdom is credited with developing the modern Thai alphabet. However, following the death of King Ramkamhaeng, the mightier state of Ayutthaya gradually exerted its influence over Sukhothai.
Following the death of King Ramkhamhaeng, the kingdom of Sukhothai rapidly declined and Lan Na expanded its influence over its neighboring kingdoms, many of which were former suzerains of Sukhothai. In the middle of the 15th Century Lan Na arts and literature reached a pinnacle during the King Tilokoraj period. However, after the king's death, Lan Na weakened due to internal conflicts and Chiang Mai fell under Burmese control around 1564; while the Burmese occupied the northern region for a few centuries, they did little development, using Chiang Mai as a military base from which to battle the Kingdom of Ayutthaya, a mighty kingdom in the central plains that was gradually exerting its influence from the mid 14 th century onwards.