Laos, officially the Lao People's Democratic Republic, is a socialist country in Southeast Asia and the region's only landlocked country. Laos is located in the center of the Indochinese Peninsula, bordered to the northwest by Myanmar and China, to the east by Vietnam, to the southeast by Cambodia, and to the west and southwest by Thailand. Present-day Laos traces its historic and cultural identity to Lan Xang, which was one of Southeast Asia's largest kingdoms from the 14th to the 18th centuries. The kingdom became a center for overland trade and prospered economically and culturally as a result of its central geographic position in Southeast Asia. Lan Xang was divided into three kingdoms after a time of internal strife: Luang Phrabang, Vientiane, and Champasak. The three territories were united in 1893 under a French protectorate to create what is now known as Laos. After a brief period of independence in 1945 following Japanese occupation, it was re-colonized by France until 1949, when it was granted autonomy. Laos gained independence in 1953, and Sisavang Vong established a constitutional monarchy. Following independence, a post-independence civil war erupted, with the communist opposition, backed by the Soviet Union, fighting the monarchy, which later fell under the control of military regimes backed by the US. The communist Pathet Lao came to power after the Vietnam War ended in 1975, putting an end to the civil war. Until the Soviet Union's collapse in 1991, Laos was reliant on military and economic assistance from the Soviet Union. Laos is a member of the ASEAN, the East Asia Summit, and La Francophonie, as well as the Asia-Pacific Trade Agreement. Laos applied to join the World Trade Organization in 1997 and was granted full membership on February 2, 2013. It is a Marxist–Leninist one-party socialist republic ruled by the Lao People's Revolutionary Party, under which non-governmental organisations have repeatedly criticized the country's human rights record, alleging torture, limitations on civil liberties, and oppression of minorities. The Lao people, who are politically and culturally dominant, account for 53.2% of the population, with the majority of them living in the lowlands. In the foothills and mountains, Mon-Khmer groups, the Hmong, and other indigenous hill tribes live. Laos' development strategies include generating electricity from rivers and selling it to its neighbors, including Thailand, China, and Vietnam, as well as a push to become a "land-linked" country, as evidenced by the construction of four new railways linking Laos and its neighbors. The World Bank has classified Laos as one of the fastest growing economies in Southeast Asia and the Pacific, with annual GDP growth averaging 7.7% since 2009.