A republic in SW Asia, between the Caspian Sea and the Persian Gulf: consists chiefly of a high central desert plateau almost completely surrounded by mountains, a semitropical fertile region along the Caspian coast, and a hot and dry area beside the Persian Gulf. Oil is the most important export. Official language: Farsi (Persian). Official religion: Muslim majority. Currency: rial. Capital: Tehran. Population: 61,531,000 (1998 est.). Area: 1,647,050 sq. km (635, 932 sq. miles). Former name (until 1935): Persia. Official name: Islamic Republic of Iran. See also Persian Empire.