Balouchistan has a population of 6,511,358 and an area of 134,000 sq mi (347,000 sq km). It is bounded by Iran on the west, by Afghanistan on the north, and by the Makran coast of the Arabian Sea on the south. Quetta is the capital; it is connected by railway to the main Indus plains corridor of Pakistan. Lying outside the monsoon zone and with few rivers usable for irrigation, Baluchistan is largely desert basins with inarable hills and mountains. Pastoral nomads who speak languages related to Persian constitute most of the sparse population. Some cotton is raised and processed, and natural gas is exploited. On the coast there is trade in fish and salt. It was incorporated into the province of West Pakistan in 1955, but returned to full provincial status in 1970. In 1976 the Pakistani central government revoked the authority of local chiefs to administer their own peoples, touching off a popular revolt against the government. Guerrilla fighting between native leaders and government forces continued into the 1980s.