The Mekong River, most of which flows in a broad valley, forms much of the boundaries with Myanmar and Thailand. For two stretches, however—one greater than 300 mi (480 km)—the Mekong flows entirely through the territory of Laos. Except for the Mekong lowlands and three major plateaus, the terrain of Laos is rugged, mountainous, and heavily forested; jagged crests in the north tower over 9,000 ft (2,740 m). In addition to the capital, important cities include Savannaket, Pakse, and Luang Phabang (the former royal capital).
Laos is one of the nations of Southeast Asia least touched by modern civilization. There are no railroads; roads and trails are limited; and use of the country's main communications artery, the Mekong River, is impeded by many falls and rapids. More than half the people live along the Mekong and its tributaries, and most are subsistence farmers. The urban areas are more prosperous, with a slowly growing middle class.
About two thirds of the population are Lao Loum, a people ethnically related to the Thai, who live along the Mekong River valley. The Lao Theung or Mountain Mon Khmer (about 22% of the population) generally reside in upland valleys. Highland groups include the Hmong (Meo), Yao (Mien), Black Thai, Dao, and several Tibeto-Burman speaking peoples. There are also important minorities of Vietnamese and Chinese. A majority of Laotians are Theravada Buddhists; although the mountain peoples are generally animists, some have adopted Buddhism. Lao is the official language; French and English are also spoken.