Tanintharyi Region historically included the entire Tanintharyi peninsula—today’s Tanintharyi Region, Mon State and southern Kayin State. The northernmost peninsula region was part of the Thaton Kingdom before 1057, and the entire coastline became part of King Anawrahta’s Pagan Empire after 1057. After the fall of Pagan in 1287, the area fell to the Siamese kingdom of Sukhothai, and later its successor Ayutthaya Kingdom.