Laos traces its formal history (also see Early History of Laos) to the establishment of the Kingdom of Lan Xang (literally, "million elephants") by King Fa Ngum in 1353. Under his rule, the wealthy and mighty kingdom covered the northeast region of present-day Thailand (Isan), all of Laos and present-day Stung Treng province of Cambodia. His successors, especially King Photisarath in the 16th century, helped establish Theravada Buddhism as the predominant religion of the country.
By the 17th century, the kingdom of Lan Xang entered a period of decline marked by dynastic struggle and conflicts with its neighbors. In the late 18th century, Siam established control over much of what is now Laos. The region was divided into principalities centered on Luang Prabang in the north, Vientiane in the center, and Champassak in the south. Following its colonization of Vietnam, France supplanted Siam and began to integrate all of Laos into the French empire. The Franco-Siamese treaty of 1907 defined the present Lao boundary with Thailand.
During World War II, the Japanese occupied French Indochina, including Laos. King Sisavang Vong of Luang Prabang was induced to declare independence from France in 1945, just prior to Japan's surrender. During this period, nationalist sentiment grew. In September 1945, Vientiane and Champassak united with Luang Prabang to form an independent government under the Free Laos (Lao Issara) banner. The movement, however, was shortlived. By early 1946, French troops reoccupied the country and conferred limited autonomy on Laos following elections for a constituent assembly.
Amidst the first Indochina war between France and the communist movement in Vietnam, Prince Souphanouvong formed the Pathet Lao (Land of Laos) resistance organization committed to the communist struggle against colonialism. Laos was not granted full sovereignty until the French defeat by the Vietnamese and the subsequent Geneva peace conference in 1954. Elections were held in 1955, and the first coalition government, led by Prince Souvanna Phouma, was formed in 1957. The coalition government collapsed in 1958, amidst increased polarization of the political process. Rightist forces took over the government.
In 1960, Kong Le, a paratroop captain, seized Vientiane in a coup and demanded formation of a neutralist government to end the fighting. The neutralist government, once again led by Souvanna Phouma, was not successful in holding power. Rightist forces under Gen. Phoumi Nosavan drove out the neutralist government from power later that same year. Subsequently, the neutralists allied themselves with the communist insurgents and began to receive support from the Soviet Union. Phoumi Nosavan's rightist regime received support from the U.S.
A second Geneva conference, held in 1961-62, provided for the independence and neutrality of Laos. Soon after accord was reached, the signatories accused each other of violating the terms of the agreement, and with superpower support on both sides, the civil war soon resumed. Although the country was to be neutral, a growing American and North Vietnamese military presence in the country increasingly drew Laos into the second Indochina war (1954-75). For nearly a decade, Laos was subjected to the heaviest bombing in the history of warfare, as the U.S. sought to destroy the Ho Chi Minh Trail that passed through eastern Laos.
In 1972, the communist People's Party renamed itself the Lao People's Revolutionary Party (LPRP). It joined a new coalition government in Laos soon after the Vientiane cease-fire agreement in 1973. Nonetheless, the political struggle between communists, neutralists, and rightists continued. The fall of Saigon and Phnom Penh to communist forces in April 1975 hastened the decline of the coalition in Laos. Months after these communist victories, the Pathet Lao entered Vientiane. On December 2, 1975, the king abdicated his throne in the constitutional monarchy, and the communist Lao People's Democratic Republic (LPDR) was established.
The new communist government led by Kaysone Phomvihane imposed centralized economic decisionmaking and broad security measures, including control of the media and the arrest and incarceration of many members of the previous government and military in "re-education camps". These draconian policies and deteriorating economic conditions, along with government efforts to enforce political control, prompted an exodus. About 10% of the Lao population sought refugee status after 1975. Along with Cuba, North Korea and Vietnam, Laos remains one of the few remaining countries under communist leadership.