Page "Sukhothai Kingdom" Paragraph 10

To the west, Ramkhamhaeng helped the Mons under Wareru ( who is said to have eloped with Ramkamhaeng ’ s daughter ) to free themselves from Pagan control and established a kingdom at Martaban ( they later moved to Pegu ).

So, Thai historians considered the Kingdom of Martaban a Sukhothai tributary.

However, in practice, such Sukhothai domination may not have extended that far.