The largest river, the Mekong (known as Nam Khong), runs the entire length of the country dividing Laos and Thailand. Over 70 percent of Laos is mountains and plateaus.
Laos has been long occupied by migrating Thais (including the Shans, Siamese and Lao) as well as the Hmongs and Mien hill tribes.
The first municipalities were consolidated in the 13th century following the invasion of south-west China by Kublai Khan's Mongol hordes. In the 14th century, scattered principalities around Luag Prabang was formed by a Khmer-sponsored warlord, Fa Ngum, to form his own kingdom called Lan Xang, meaning "a millian elephants." The kingdom eventually prospered, but internal divisions and neighboring pressure caused it to split in the 17th century into three warring kindoms cenetered on Luang Prabang, Wieng Chan (or Vientiane) and Champasak.
By the end of the 18th century, most of Laos came under Siamese (or Thai) control. Eventually, in the 1820s the country went into war with Siam and fell into Siam's control. In the late 19th century France had colonized Tonkin and Annam of Vietnam and the Thais gave Laos to the French. France used Laos merely as a buffer between it's colonies in Vietnam and Siam.
During World War II, the Japanese occupied Indochina and a Lao resistance group, Lao Issara, was formed to prevent the return of the French into Laos. Lao independence was achieved in 1953. Conflict continues to persist between royalist, neutralist and communist factions. Due to it's strategic location, Ho Chi Minh dug his Ho Chi Minh trail through eastern Laos to get his armory and equipments around the US barricades in central Vietnam to get to South Vietnam. In 1964, conflict escalated between the royalist Vientiane government and the communist Pathet Lao who faught alongside the Nort Vietnamese. By 1973, Laos had become the most bombed country in the history of warfare.
A coalition government was eventually formed. However, when Saigon fell in 1975, most of the royalists left for France. Many who fought against the communist, were sent to Australia, the United States as well as France and French countries such as Canada and French Guinea. The Pathet Lao took control of Laos in December 1975. Laos entered the AEAN in July of 1997. In 1998 the former prime minister, Khamtai, became president.