Pho Khun Ban Muang and his brother Ram Khamhaeng expanded the Sukhothai kingdom. To the south, Ramkamhaeng subjugated the kingdom of Supannabhum and Sri Thamnakorn (Tambralinga) and, through Tambralinga, adopted Theravada as state religion. Although traditional history described the extension of Sukhothai in a great fashion, the accuracy of these claims is disputed. To the north, Ramkamhaeng put Phrae and Muang Sua (Luang Prabang) under tribute.
To the west, Ramkhamhaeng helped the Mons under Wareru (who is said to have eloped with Ramkamhaeng’s daughter) to free themselves from Pagan domination and establish a kingdom at Martaban (they later moved to Pegu). So, Thai historians considered the Kingdom