Champasak (or Champassak, Champasack – Lao: ຈໍາປາສັກ t͡ɕàm pàː sák) is a province in southwestern Laos, near the borders with Thailand and Cambodia. It is one of the three principalities that succeeded the Lao kingdom of Lan Xang. As of the 2015 census, it had a population of 694,023. The capital is Pakse, but the province takes its name from Champasak, the former capital of the Kingdom of Champasak. Champasak is bordered by Salavan province to the north, Sekong province to the northeast, Attapeu province to the east, Cambodia to the south, and Thailand to the west. The Mekong River forms part of the border with neighboring Thailand and contains Si Phan Don ('Four Thousand Islands') in the south of the province, on the border with Cambodia. Champasak has played a central role in the history of Siam and Laos, with frequent battles taking place in and around Champasak. Its cultural heritage includes ancient temple ruins and French colonial architecture. Champasak has some 20 wats (temples), such as Wat Phou, Wat Luang, and Wat Tham Fai. Freshwater dolphins and the province's many waterfalls are tourist attractions. From the 1st to 9th centuries CE, Champasak province was part of the Funan and then Chenla Kingdoms. Between the 10th and 13th centuries it was part of the Khmer Empire. In 1354, the area came under the control of King Fa Ngum and the Lan Xang Empire. The Angkor empire went into decline between the 15th and 17th centuries when it was annexed by Lan Xang. In 1707, Champasak became one of three kingdoms arising from a dissolved Lan Xang Empire. The kingdom had only three kings, Soi Sisamut (1713–37), nephew of Suriya Vangas, Sainya Kuman (1737–91) and lastly Fai Na (1791–1811). In 1829 Siam annexed Champassak following the Chao Anouvong Rebellion. Pakse, the capital of the province, was established by the French in 1905 as an administrative outpost at the confluence of Xe Don (Don River) and the Mekong. Champasak province covers an area of .