Iran's central position has made it a crossroads of migration; the population is not homogeneous, although it has a Persian core that includes over half of the people. Azerbaijanis constitute almost a quarter of the population. The migrant ethnic groups of the mountains and highlands, including the Kurds, Lurs, Qashqai, and Bakhtiari, are of the least mixed descent of the ancient inhabitants. In the northern provinces, Turkic and Tatar influences are evident; Arab strains predominate in the southeast. Iran has a large rural population, found mainly in agrarian villages, although there are nomadic and seminomadic pastoralists throughout the country.
Islam entered the country in the 7th cent. A.D. and is now the official religion; about 90% of Iranians are Muslims of the Shiite sect. The remainder, mostly Kurds and Arabs, are Sunnis. Colonies of Zoroastrians (see Zoroastrianism) remain at Yazd, Kerman, and other large towns. In addition to Armenian and Assyrian Christian sects, there are Jews, Protestants, and Roman Catholics. Attempts have been made to suppress Babism and its successor, Baha'i, whose adherents constitute about 1% of Iran's population; Sufism has also suffered from government restrictions under the Islamic republic. Other religious movements, such as Mithraism (see under Mithra) and Manichaeism, originated in Iran.
The principal language of the country is Persian (Farsi), which is written with the Arabic alphabet and spoken by about 60% of the people. Other groups speak Turkic dialects (25%), Kurdish, (10%), and Turkish, Armenian, and Arabic. Among the educated classes, English and French are spoken.