Muang Sua, nowadays known as
Luang Prabang, was named in 698 following its conquest, by the Lao prince
Khun Lo, who was awarded the town by his father
Khun Borom. In the second half of the eighth century, Nanzhao intervened frequently in the affairs of the principalities of the middle
Mekong Valley, resulting in the occupation of Muang Sua in 709. Nanzhao princes or administrators replaced the aristocracy of Tai overlords. Dates of the occupation are not known, but it probably ended well before the northward expansion of the
Khmer Empire under
Indravarman I (reigned 877–889) and extended as far as the territories of
Sipsong Panna on the upper Mekong. Recent historical research has shown that the
Mongols, who destroyed
Dali 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 (lord), 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.
Ram Khamhaeng, 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 IX, whose kingdom had acknowledged Mongol suzerainty since 1285. The younger brother,
Fa Ngum, married one of the king's daughters and in 1349 set out from
Angkor at the head of a 10,000-man army. His conquest of the territories to the north of Angkor over the next six years reopened Mongol communications with that place, which had been cut off. Fa Ngum organized the conquered principalities into provinces, and reclaimed Muang Sua from his father and elder brother. Fa Ngum was crowned king of Lan Xang at
Vientiane, the site of one of his victories, in June 1354. Lan Xang extended from the border of China to Sambor below the Mekong rapids at
Khong Island and from the Vietnamese border to the western escarpment of the
Khorat Plateau. ==List of rulers==