The Lao people migrated into Laos from southern China from the 8th century onward. In the 14th century, the first Laotian state was founded, the Lan Xang kingdom, which ruled Laos until it split into three separate kingdoms in 1713. During the 18th century, the three kingdoms came under Siamese (Thai) rule and, in 1893, became a French protectorate. With its territory incorporated into Indochina. A strong nationalist movement developed during World War II, but France reestablished control in 1946 and made the king of Luang Prabang constitutional monarch of all Laos. France granted semiautonomy in 1949 and then, spurred by the Viet Minh rebellion in Vietnam, full independence within the French Union in 1950.
In 1951, Prince Souphanouvong organized the Pathet Lao, a Communist independence movement, in North Vietnam. Viet Minh and Pathet Lao forces invaded central Laos, resulting in civil war. By the Geneva Agreements of 1954 and an armistice of 1955, two northern provinces were given to the Pathet Lao; the rest went to the royal regime. Full sovereignty was given to the kingdom by the Paris Agreements of Dec. 29, 1954. In 1957, Prince Souvanna Phouma, the royal prime minister, and Pathet Lao leader Prince Souphanouvong, the prime minister’s half-brother, agreed to reestablishment of a unified government, with Pathet Lao participation and integration of Pathet Lao forces into the royal army. The agreement broke down in 1959, and armed conflict began anew.
In 1960, the struggle became a three-way fight as Gen. Phoumi Nosavan, controlling the bulk of the royal army, set up in the south a pro-Western revolutionary government headed by Prince Boun Oum. General Phoumi took Vientiane in December, driving Souvanna Phouma into exile in Cambodia. The Soviet bloc supported Souvanna Phouma. In 1961, a cease-fire was arranged and the three princes agreed to a coalition government headed by Souvanna Phouma.