Iran (ērän', ĭrăn') , officially Islamic Republic of Iran, republic (2005 est. pop. 68,018,000), 636,290 sq mi (1,648,000 sq km), SW Asia. The country's name was changed from Persia to Iran in 1935. Iran is bordered on the north by Armenia, Azerbaijan, Turkmenistan, and the Caspian Sea; on the east by Afghanistan and Pakistan; on the south by the Persian Gulf and the Gulf of Oman; and on the west by Turkey and Iraq. The Shatt al Arab forms part of the Iran-Iraq border. Tehran is the capital, largest city and the political, cultural, commercial, and industrial center of the nation.

Land

Physiographically, Iran lies within the Alpine-Himalayan mountain system and is composed of a vast central plateau rimmed by mountain ranges and limited lowland regions. Iran is subject to numerous and often severe earthquakes and volcanic eruptions. The Iranian Plateau (alt. c.4,000 ft/1,200 m), which extends beyond the low ranges of E Iran into Afghanistan, is a region of interior drainage. It consists of a number of arid basins of salt and sand, such as those of Dasht-e Kavir and Dasht-e Lut, and some marshlands, such as the area around Hamun-i-Helmand along the Afghanistan border. The plateau is surrounded by high folded and volcanic mountain chains including the Kopet Mts. in the northwest, the Elburz Mts. (rising to 18,934 ft/5,771 m at Mt. Damavand, Iran's highest point) in the north, and the complex Zagros Mts. in the west. Lake Urmia, the country's largest inland body of water, is in the Zagros of NW Iran. Narrow coastal plains are found along the shores of the Persian Gulf, Gulf of Oman, and the Caspian Sea; at the head of the Persian Gulf is the Iranian section of the Mesopotamian lowlands. Of the few perennial rivers in Iran, only the Karun in the west is navigable for large craft; other major rivers are the Karkheh and the Sefid Rud.
The climate of Iran is continental, with hot summers and cold, rainy winters; the mountain regions of the north and west have a subtropical climate. Temperature and precipitation vary with elevation, as winds bring heavy moisture from the Persian Gulf. The Caspian region receives over 40 in. (102 cm) of rain annually. Precipitation occurs mainly in the winter and decreases from northwest to southeast; much of the precipitation in the mountains is in the form of snow. Meltwater is vital for Iran's water supply. The central portion of the plateau and the southern coastal plain (Makran) receive less than 5 in. (12.7 cm) of rain annually.
The country is divided into 30 provinces. In addition to Tehran, important cities include Esfahan, Mashhad, Tabriz, Rasht, Hamadan, Abadan, Shiraz, and Ahvaz.

People

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 original Iranians. 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. 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 in Arabic characters. Other languages are Turkic dialects, Turkish, Kurdish, Armenian, and Arabic. Among the educated classes, English and French are spoken.

Economy

About 10% of the land in Iran is arable; agriculture contributes just over 20% to the gross national product and employs a third of the labor force. The main food-producing areas are in the Caspian region and in the valleys of the northwest. Wheat, the most important crop, is grown mainly in the west and northwest; rice is the major crop in the Caspian region. Barley, corn, cotton, sugar beets, tea, hemp, tobacco, fruits (including citrus), nuts, and dates are also grown, and livestock is raised. Illicit cultivation of the opium poppy is fairly common.
The principal obstacles to agricultural production are primitive farming methods, overworked and underfertilized soil, poor seed, and scarcity of water. About one third of the cultivated land is irrigated; the construction of multipurpose dams and reservoirs along the rivers in the Zagros and Elburz mts. has increased the amount of water available for irrigation. Agricultural programs of modernization, mechanization, and crop and livestock improvement, and programs for the redistribution of land are increasing agricultural production.
The northern slopes of the Elburz Mts. are heavily wooded, and forestry products are economically important; the cutting of trees is rigidly controlled by the government, which also has a reforestation program. In the rivers entering the Caspian Sea are salmon, carp, trout, and pike; sturgeon are abundant in the Caspian Sea.
Of the variety of natural resources found in Iran, petroleum (discovered in 1908 in Khuzestan province) and natural gas are by far the most important. The chief oil fields are found in the central and southwestern parts of the Zagros Mts. in W Iran. Oil also is found in N Iran and in the offshore waters of the Persian Gulf. Domestic oil and gas, along with hydroelectric power facilities, provide the country with power.
The petroleum industry is Iran's economic mainstay; oil accounts for 80% of export revenues, and Iran is a member of the Organization of Petroleum Exporting Countries (OPEC). Major refineries are located at Abadan (site of the country's first refinery, built 1913), Kermanshah, and Tehran. Pipelines move oil from the fields to the refineries and to such exporting ports as Abadan, Bandar-e Mashur, and Khark Island. In the late 1990s, Iran's state-owned oil and gas industry entered into major exploration and production agreements with foreign consortiums.
Textiles are the second most important industrial product; Tehran and Esfahan are the chief textile-producing centers. Other major industries are sugar refining, food processing, and the production of petrochemicals, cement and other building materials, and machinery. There is an iron and steel plant at Esfahan and a fertilizer plant at Shiraz. Traditional handicrafts such as carpet weaving and the manufacture of ceramics, silk, and jewelry are also important to the economy.
Besides crude and refined petroleum, Iran's chief exports are carpets, fruits, nuts, hides, and iron and steel; its chief imports are machinery, metals, military supplies, food, and chemicals. Iran's chief trading partners are Japan, Germany, and Italy. Khorramshahr, on the Shatt al Arab, is the country's chief general cargo port; Bandar-e Anzali is the chief Caspian port. A network of roads links the villages with the larger cities; most of the principal routes are paved. The Trans-Iranian RR links N Iran with the Persian Gulf.

Government

Iran is a theocratic Islamic republic governed under the constitution of 1979, as revised in 1989, when presidential powers were expanded and the post of prime minister eliminated. Appointed, rather than elected, offices and bodies hold the real power in the government. The supreme leader, who effectively serves as the chief of state, is appointed for life by an Islamic religious advisory board (the Assembly of Experts). The supreme leader oversees the military and judiciary and appoints members of the Guardian Council and the Expediency Discernment Council. The former, some of whose members are appointed by the judiciary and approved by parliament, works in close conjunction with the government and must approve both candidates for political office and legislation passed by parliament. The latter is a body responsible for resolving disputes between parliament and the Guardian Council over legislation. The president, who is popularly elected for a four-year term, serves as the head of government. The legislative branch consists of the 290-seat Islamic consultative assembly, or parliament, whose members are elected by popular vote for four-year terms.

History

Early History to the Zand Dynasty
Iran has a long and rich history. For a detailed description of the Persian Empire, see Persia. Some of the world's most ancient settlements have been excavated in the Caspian region and on the Iranian plateau; village life began there c.4000 B.C. The Aryans came about 2000 B.C. and split into two main groups, the Medes and the Persians. The Persian Empire founded (c.550 B.C.) by Cyrus the Great was succeeded, after a period of Greek and Parthian rule, by the Sassanid in the early 3d cent. A.D. Their control was weakened when Arab invaders took (636) the capital, Ctesiphon; it ended when the Arabs defeated the Sassanid armies at Nahavand in 641. With the invasion of Persia the Arabs brought Islam. The Turks began invading in the 10th cent. and soon established several Turkish states. The Turks were followed by the Mongols, led by Jenghiz Khan in the 13th cent. and Timur in the late 14th cent.
The Safavid dynasty (1502–1736), founded by Shah Ismail, restored internal order in Iran and established the Shiite sect of Islam as the state religion; it reached its height during the reign (1587–1629) of Shah Abbas I (Abbas the Great). He drove out the Portuguese, who had established colonies on the Persian Gulf early in the 16th cent. Shah Abbas also established trade relations with Great Britain and reorganized the army. Religious differences led to frequent wars with the Ottoman Turks, whose interest in Iran was to continue well into the 20th cent.
The fall of the Safavid dynasty was brought about by the Afghans, who overthrew the weak shah, Husein, in 1722. An interval of Afghan rule followed until Nadir Shah expelled them and established (1736) the Afshar dynasty. He invaded India in 1738 and brought back fabulous wealth, including the legendary Peacock Throne and the Koh-i-noor diamond. Nadir Shah, a despotic ruler, was assassinated in 1747. The Afshar dynasty was followed by the Zand dynasty (1750–94), founded by Karim Khan, who established his capital at Shiraz and adorned that city with many fine buildings. His rule brought a period of peace and renewed prosperity. However, the country was soon again in turmoil, which lasted until the advent of Aga Muhammad Khan.