Muang Sua was the old name of Luang Phrabang following its conquest in 698 A.D. by a Thai prince, Khun Lo, who seized his opportunity when Nan-chao[?] was engaged elsewhere. Khun Lo had been awarded the town by his father, Khun Borom, who is associated with the Lao legend of the creation of the world, which the Lao share with the Shan and other peoples of the region. Khun Lo established a dynasty whose fifteen rulers reigned over an independent Muang Sua for the better part of a century.
In the second half of the 8th century, Nan-chao intervened frequently in the affairs of the principalities of the middle Mekong Valley, resulting in the occupation of Muang Sua in 709. Nan-chao princes or administrators replaced the aristocracy of Thai overlords. Dates of the occupation are not known, but it probably ended well before the northward expansion of the Khmer Empire under Indravarman I[?] (r. 877-89) and extended as far as the territories of Sipsong Panna[?] on the upper Mekong.
In the meantime, the Khmers founded an outpost at Xay Fong[?] near Vientiane, and Champa expanded again in southern Laos, maintaining its presence on the banks of the Mekong until 1070. Chanthaphanit[?], the local ruler of Xay Fong, moved north to Muang Sua and was accepted peacefully as ruler after the departure of the Nan-chao administrators. Chanthaphanit and his son had long reigns, during which the town became known by the Thai name Xieng Dong Xieng Thong[?]. The dynasty eventually became involved in the squabbles of a number of principalities. Khun Chuang[?], a warlike ruler who may have been a Kammu (alternate spellings include Khamu and Khmu[?]) tribesman, extended his territory as a result of the warring of these principalities and probably ruled from 1128 to 1169. Under Khun Chuang, a single family ruled over a far-flung territory and reinstituted the Siamese administrative system of the seventh century. At some point, Theravada Buddhism was subsumed by Mahayana Buddhism.
Xieng Dong Xieng Thong experienced a brief period of Khmer suzerainty under Jayavarman VII from 1185 to 1191. By 1180 the Sipsong Panna had regained their independence from the Khmers, however, and in 1238 an internal uprising in the Khmer outpost of Sukhodaya expelled the Khmer overlords.
Xieng Dong Xieng Thong in 1353 became the capital of Lan Xang.