Laos was under the control 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. In 1975, the Communist Pathet Lao took control of the government, ending a six-century-old monarchy. Initial closer ties to Vietnam and socialization were replaced with a gradual return to private enterprise, a liberalization of foreign investment laws, and the admission into ASEAN in 1997.