Fars (färs) [key] or Farsistan färsĭstänˈ, province (1991 pop. 3,543,828), c.51,500 sq mi (133,400 sq km), SW Iran. Shiraz is the capital and chief city, located in an oasis occupying a valley c.6 mi (10 km) wide and 20 mi (32 km) long. The province is largely mountainous. Grain, cotton, tobacco, opium, fruit, and wine are produced along the coastal Persian Gulf area. Livestock is raised. Oil and natural gas reserves have stimulated the local economy. Industries include food processing and the manufacture of chemicals, fertilizers, and textiles. The population is mostly organized by tribe; the leading tribes are the Qashqai and the Khamseh. One of the most historic regions of Iran, Fars is more or less identical with the ancient province of Pars, which was the nucleus of the Persian Empire. The ruins of Pasargadae and Persepolis, early Persian capitals, are in Fars. The Arabs changed the name Pars to Fars after they conquered the region in the 7th cent.