family. From 1941–45 Thailand exploited France's weakness during World War II to acquire Champasak and other Lao lands on the right bank of the Mekong. In 1946 Champasak was ceded back to France and Chao Boun Oum remitted all claims to an independent kingship in order to unify Laos. The Kingdom of Laos (1946–75) was then formed under the Luang Prabang line of kingship. Kings Kingdom of Luang Prabang (1707–1893) & French Protectorate of Laos (1893-1947) With the division of Lan Xang, the city of Luang Prabang recovered its prestige as a royal city, since the capital had moved to Vientiane with Setthathirath in 1560. The city was a growing center for religion and trade, but remained politically weak and would be sacked by the Burmese in 1764. Throughout the 18th and 19th centuries the Kingdom endured as a vassal to China, Siam, Burma, and Vietnam. In 1828 following Chao Anouvong's Rebellion the kingdom was annexed by Siam. Despite their vassal status the Kings of Luang Prabang exercised a degree of autonomy, but lacked the security apparatus to effectively defend the kingdom (which may have been used in rebellion, as had been done in the kingdoms of Vientiane and Champasak). As a result, throughout the mid-19th century Haw pirates from China were able to invade. Kings Principality of Xiang Khouang (Muang Phuan) (1707–1899) The Muang of Xiang Khouang was a semi-autonomous region in Laos in what is now Xiang Khouang province. The Phuan (Pu’on) monarchy claims descent from Khun Borom and were part of the Lan Xang mandala. Geographic isolation and frequent warfare produced periods where the Phuan kings tried to assert more authority, but the region remained only a key vassalage for surrounding kingdoms. The region features prominently in the 18th and 19th century as valuable coalition piece for the rival kingdoms of Vientiane and Champasak. Xiang Khouang was a trade frontier, and also frequent point of invasion, and so has more cultural influences from China and Vietnam. Kings Kingdom of Laos (1947–1975) The Kingdom of Laos created in 1947 marked the first time the kingdoms of Laos had been unified since the division of Lan Xang in 1707. The Franco-Lao Treaty of 1953, gave Laos independence and the Royal Lao Government took control of the country. This treaty established a constitutional monarchy, with Sisavang Vong as King and Prince Souvanna Phouma as Prime Minister. In 1959, after the