元史
According to the Chinese "History of Yuan", King Ram Khamhaeng died in 1298 and was succeeded by his son, Loe Thai, though George Cœdès thinks it "more probable" it was "shortly before 1318". Legend states he disappeared in the rapids of the rivers of Sawankhalok. Another possible source states he was slain by a Malay warrior princess named Adruja Sriwijayamala Singha during a battle between Thai and Malay armies, in a campaign to conquer Malay lands that make up a third of modern Thailand today.