Located in Southeast Asia, Laos is a small, landlocked, and mountainous country. The first united Lao kingdom known as Lan Xang was founded in 1353 and included much of modern Thailand. After centuries of gradual decline, Laos came under the domination of Siam (Thailand) from the late 18th century until the late 19th century when it became part of French Indochina. The Franco-Siamese Treaty of 1907 defined the current Lao border with Thailand. Laos gained full independence as a constitutional monarchy in 1954. In 1975, Communist forces took control of the government, ending a six-century-old monarchy and instituting a strict socialist regime. Since coming to power, the communist government imposed a command economy system, replacing the private sector with state enterprises and cooperatives. The Lao government began decentralizing control and encouraging private enterprise in the mid-1980s, and the country began opening up to the world in the 1990s. However, Laos today remains one of the poorest and least developed countries in the world.