Many parts of the country do not have schools. For Cambodia's literacy rate, see . Cambodian women Land. Low mountains border Cambodia, except in the southeast and along part of the coast. The great Mekong River flows south from Laos through Cambodia and enters the South China Sea through Vietnam.
Fertile plains cover about a third of the land, and forests cover much of the rest.
During the dry season, the Tonle Sap River flows southeast from the shallow Tonle Sap and joins the Mekong at Phnom Penh. The river does this because floods and melted snow from the Mekong's source in Tibet make the river rise to a level higher than that of the lake. The rainy season lasts from May to November. Cambodia's economy is based chiefly on agriculture. Until the 1970's, the country's farm production was usually high enough to provide food for the Cambodian people and also exports to other countries.