1239 - Reign of Sri Indraditya at Sukhothai under Khmer rule Ca. 1239 - Ca. 1259 [Reference: Wyatt, David K. (2003) - Thailand, A short history (2nd Ed.) - Silkworm Books]
1247 - Circa 1247, Pha Mueang, the lord of the small principality of Mueang Rat, gathered an army and joined with those of a neighbouring Siamese ruler, Bang Klang Hao of Mueang Bang Yang, who had not submitted to the Khmer. After reducing nearby Bang Khlang and Satchanalai, they marched on the main Khmer outpost in the region at Sukhothai. The Khmer gave battle but were defeated, and Pha Mueang entered the city. Pha Mueang then presented his conquest to his ally, Bang Klang Hao, together with his own title and sword, and he presided over the new Sri Indraditya’s coronation as king of Sukhothai. [Reference: Wyatt, David K. (2003) - Thailand, A short history (2nd Ed.) - Silkworm Books - page 43]
1259 - Ban Mueang ascends the throne of Sukhothai, Ca. 1259 - Ca. 1279 [Reference: Wyatt, David K. (2003) - Thailand, A short history (2nd Ed.) - Silkworm Books]
1262 - Establishment of the City of Chiang Rai in 1262 by King Mengrai.
1279 - Death of King Ban Mueang of Sukhothai and throne ascendance of King Ramkhamhaeng (reign ca. 1279-1298) [Reference: Wyatt, David K. (2003) - Thailand, A short history (2nd Ed.) - Silkworm Books]