Fa Ngum's campaign started in southern Laos, taking the towns and cities in the region around Champasak and moving northward through Thakek and Kham Muang along the middle Mekong. From his position on the middle Mekong, Fa Ngum sought assistance and supply from Vientiane in attacking Muang Sua, which they refused. However, Prince Nho of Muang Phuan (Muang Phoueune) offered assistance and vassalage to Fa Ngum for assistance in a succession dispute of his own and help in securing Muang Phuan from Đại Việt. Fa Ngum agreed and quickly moved his army to take Muang Phuan and then on to take Xam Neua and several smaller towns of Đại Việt.