Recent historical research has shown that the Mongols, who destroyed Nan-chao in 1253 and made the area a province of their empire--naming it Yunnan--exercised a decisive political influence in the middle Mekong Valley for the better part of a century. In 1271 Panya Lang, founder of a new dynasty headed by rulers bearing the title panya, began his rule over a fully sovereign Muang Sua. In 1286 Panya Lang's son, Panya Khamphong, was involved in a coup d'état that was probably instigated by the Mongols and that exiled his father. Upon his father's death in 1316, Panya Khamphong assumed his throne.

Ramkhamhaeng, an early ruler of the new Thai dynasty in Sukhothai, made himself the agent of Mongol interests, and in 1282- 84 eliminated the vestiges of Khmer and Cham power in central Laos. Ramkhamhaeng obtained the allegiance of Muang Sua and the mountainous country to the northeast. Between 1286 and 1297, Panya Khamphong's lieutenants, acting for Ramkhamhaeng and the Mongols, pacified vast territories. From 1297 to 1301, Lao troops under Mongol command invaded Dai Viet but were repulsed by the Vietnamese. Troops from Muang Sua conquered Muang Phuan in 1292-97. In 1308 Panya Khamphong seized the ruler of Muang Phuan, and by 1312 this principality was a vassal state of Muang Sua.

Mongol overlordship was unpopular in Muang Sua. Internal conflicts among members of the new dynasty over Mongol intervention in their affairs resulted in continuing family upheavals. Panya Khamphong exiled his son Fa Phi Fa and most likely intended to leave the throne to his younger grandson, Fa Ngieo. Fa Ngieo, involved in various coups and coup attempts, in 1330 sent his two sons to a Buddhist monastery outside the Mongol realm for safety. The brothers were kidnapped in 1335 and taken to Angkor, where they were entrusted to King Jayavarman Paramesvara, whose kingdom had acknowledged Mongol suzerainty since 1285.

Data as of July 1994