King Mangrai was born on October 2, 1238 in Ngoen Yang (present day Chiang Saen) Thailand on the Mekong River, a son of the local ruler Lao Meng and his wife Ua Ming Chom Mueang, a princess from the Tai Lue city of Chiang Rung, which is now called Jinghong, in Sipsongpanna (Xishuangbanna), China.