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Zagros Mountains [Credit: Fred J. Maroon/Photo Researchers]Zagros MountainsFred J. Maroon/Photo ResearchersThe Zagros (Zāgros) Mountains stretch in a northwest-southeast direction, from Iran’s borders with Turkey and Iraq in the northwest to the Strait of Hormuz in the southeast. Farther to the south the range broadens into a band of parallel ridges 125 miles (200 km) wide that lies between the plains of Mesopotamia and the great central plateau of Iran. The range is drained on the west by streams that cut deep narrow gorges and water fertile valleys. The land is extremely rugged and difficult to access and is populated largely by pastoral nomads.

Māzandarān [Credit: Robert Harding Picture Library]MāzandarānRobert Harding Picture LibraryThe Elburz (Alborz) Mountains run along the south shore of the Caspian Sea to meet the border ranges of the Khorāsān region to the east. The tallest peak in the chain is the snow-clad Mount Damāvand (Demavend), which is also Iran’s highest point. Many parts of Iran are isolated and poorly surveyed, and the elevation of many of its peaks are still in dispute; the height of Mount Damāvand is generally given as 18,605 feet (5,671 metres).

Volcanic and tectonic activity

Mount Taftān, a massive cone reaching 13,261 feet (4,042 metres) in southeastern Iran, emits gas and mud at sporadic intervals. In the north, however, Mount Damāvand has been inactive in historical times, as have Mount Sabalān (15,787 feet [4,812 metres]) and Mount Sahand (12,172 feet [3,710 metres]) in the northwest. The Sahand-Bazman Belt, formed by Eocene volcanism, extends some 1,200 miles (1,900 km) from the border with Azerbaijan in the northwest to Baluchistan in the southeast and includes volcanic peaks such as Mount Sahand, Mount Karkas in Eṣfahān province, Mount Lalahezar in Kermān province, and Bazman in Sīstān va Balūchestān province. In addition, in the northwestern section of the country, lava and ashes cover a 200-mile (320-km) stretch of land from Jolfā on the border with Azerbaijan eastward to the Caspian Sea. A third volcanic region, which is 250 miles (400 km) long and 40 miles (65 km) wide, runs between Lake Urmia (Orūmiyyeh) and the city of Qazvīn.

Earthquake activity is frequent and violent throughout the country. During the 20th century—when reliable records were available—there were fully a dozen earthquakes of 7.0 or higher on the Richter scale that took large numbers of lives. In 1990 as many as 50,000 people were killed by a powerful tremor in the Qazvīn-Zanjān area. In 2003 a relatively weak quake struck the ancient town of Bam in eastern Kermān province, leveling the town and destroying a historic fortress. More than 25,000 people perished.

The interior plateau

Kavīr Desert [Credit: Harrison Forman]Kavīr DesertHarrison FormanThe arid interior plateau, which extends into Central Asia, is bounded on the west by the Zagros Mountains, on the north by the Elburz Mountains and the Kopet-Dag (Koppeh Dāgh) Range, and on the south by the Bashagard Range, which extends east from the Strait of Hormuz into the Baluchistan region of Iran. The plateau is cut by several smaller mountain ranges. In the flatlands lie the plateau’s most-remarkable features, the Kavīr and Lūt deserts, also called the Dasht-e Kavīr and Kavīr-e Lūt. At the lowest elevations, series of basins in the poorly drained soil remain dry for months at a time; the evaporation of any accumulated water produces the salt wastes known as kavīrs. As elevation rises, surfaces of sand and gravelly soil gradually merge into fertile soil on the hillsides and mountain slopes.


Dezfūl [Credit: Fred J. Maroon/Photo Researchers]DezfūlFred J. Maroon/Photo ResearchersThe few streams emptying into the desiccated central plateau dissipate in saline marshes. The general drainage pattern is down the outward slopes of the mountains, terminating in the sea. There are three large rivers, but only one—the Kārūn—is navigable. It originates in the Zagros Mountains and flows south to the Shatt Al-Arab (Arvand Rūd), which empties into the Persian Gulf. The Sefīd (Safid) River originates in the Elburz Mountains in the north and runs as a mountain stream for most of its length but flows rapidly into the Gīlān plain and then to the Caspian Sea. The Dez Dam in Dezfūl is one of the largest in the Middle East. The Sefīd River Dam, completed in the early 1960s at Manjīl, generates hydroelectric power and provides water for irrigation.

Kārūn River [Credit: Dennis Briskin/Tom Stack & Associates]Kārūn RiverDennis Briskin/Tom Stack & AssociatesThe Zāyandeh River, the lifeline of Eṣfahān province, also originates in the Zagros Mountains, flowing southeastward to Gāv Khūnī Marsh (Gāvkhāneh Lake), a swamp northwest of the city of Yazd. The completion of the Kūhrang Dam in 1971 diverted water from the upper Kārūn through a tunnel 2 miles (3 km) long into the Zāyandeh for irrigation purposes.

Other streams are seasonal and variable: spring floods do enormous damage, while in summer many streams disappear. However, water is stored naturally underground, finding its outlet in springs and tap wells.

The largest inland body of water, Lake Urmia, in northwestern Iran, covers an area that varies from about 2,000 to 2,300 square miles (5,200 to 6,000 square km). Other lakes are principally seasonal, and all have a high salt content.






Plant and animal life









Ethnic groups

Iran is a culturally diverse society, and interethnic relations are generally amicable. The predominant ethnic and cultural group in the country consists of native speakers of Persian. But the people who are generally known as Persians are of mixed ancestry, and the country has important Turkic and Arab elements in addition to the Kurds, Baloch, Bakhtyārī, Lurs, and other smaller minorities (Armenians, Assyrians, Jews, Brahuis, and others). The Persians, Kurds, and speakers of other Indo-European languages in Iran are descendants of the Aryan tribes that began migrating from Central Asia into what is now Iran in the 2nd millennium bc. Those of Turkic ancestry are the progeny of tribes that appeared in the region—also from Central Asia—beginning in the 11th century ad, and the Arab minority settled predominantly in the country’s southwest (in Khūzestān, a region also known as Arabistan) following the Islamic conquests of the 7th century. Like the Persians, many of Iran’s smaller ethnic groups chart their arrival into the region to ancient times.

Kurdish settlement [Credit: Encyclopædia Britannica, Inc.]Kurdish settlementEncyclopædia Britannica, Inc.The Kurds have been both urban and rural (with a significant portion of the latter at times nomadic), and they are concentrated in the western mountains of Iran. This group, which constitutes only a small proportion of Iran’s population, has resisted the Iranian government’s efforts, both before and after the revolution of 1979, to assimilate them into the mainstream of national life and, along with their fellow Kurds in adjacent regions of Iraq and Turkey, has sought either regional autonomy or the outright establishment of an independent Kurdish state in the region.

Also inhabiting the western mountains are seminomadic Lurs, thought to be the descendants of the aboriginal inhabitants of the country. Closely related are the Bakhtyārī tribes, who live in the Zagros Mountains west of Eṣfahān. The Baloch are a smaller minority who inhabit Iranian Baluchistan, which borders on Pakistan.

Qashqāʾī [Credit: © R. & S. Michaud/Woodfin Camp & Associates]Qashqāʾī© R. & S. Michaud/Woodfin Camp & AssociatesThe largest Turkic group is the Azerbaijanians, a farming and herding people who inhabit two border provinces in the northwestern corner of Iran. Two other Turkic ethnic groups are the Qashqāʾī, in the Shīrāz area to the north of the Persian Gulf, and the Turkmen, of Khorāsān in the northeast.

The Armenians, with a different ethnic heritage, are concentrated in Tehrān, Eṣfahān, and the Azerbaijan region and are engaged primarily in commercial pursuits. A few isolated groups speaking Dravidian dialects are found in the Sīstān region to the southeast.

Semites—Jews, Assyrians, and Arabs—constitute only a small percentage of the population. The Jews trace their heritage in Iran to the Babylonian Exile of the 6th century bc and, like the Armenians, have retained their ethnic, linguistic, and religious identity. Both groups traditionally have clustered in the largest cities. The Assyrians are concentrated in the northwest, and the Arabs live in Khūzestān as well as in the Persian Gulf islands.










The two cornerstones of Iranian Shīʿism are the promise of the return of the divinely inspired 12th imam—Muḥammad al-Mahdī al-Ḥujjah, whom Shīʿites believe to be the mahdi—and the veneration of his martyred forebears. The absence of the imam contributed indirectly to the development in modern Iran of a strong Shīʿite clergy whose penchant for status, particularly in the 20th century, led to a proliferation of titles and honorifics unique in the Islamic world. The Shīʿite clergy have been the predominant political and social force in Iran since the 1979 revolution.

Eṣfahān: Māder-e Shah [Credit: Ray Manley/Shostal Associates]Eṣfahān: Māder-e ShahRay Manley/Shostal AssociatesThere is no concept of ordination in Islam. Hence, the role of clergy is played not by a priesthood but by a community of scholars (Arabic ʿulamāʾ). To become a member of the Shīʿite ʿulamāʾ, a male Muslim need only attend a traditional Islamic college, or madrasah. The main course of study in such an institution is Islamic jurisprudence (Arabic fiqh), but a student need not complete his madrasah studies to become a faqīh, or jurist. In Iran such a low-level clergyman is generally referred to by the generic term mullah (Arabic al-mawlā, “lord”; Persian mullā) or ākhūnd or, more recently, rūḥānī (Persian: “spiritual”). To become a mullah, one need merely advance to a level of scholarly competence recognized by other members of the clergy. Mullahs staff the vast majority of local religious posts in Iran.

An aspirant gains the higher status of mujtahid—a scholar competent to practice independent reasoning in legal judgment (Arabic ijtihād)—by first graduating from a recognized madrasah and obtaining the general recognition of his peers and then, most important, by gaining a substantial following among the Shīʿite community. A contender for this status is ordinarily referred to by the honorific hojatoleslām (Arabic ḥujjat al-Islām, “proof of Islam”). Few clergymen are eventually recognized as mujtahids, and some are honoured by the term ayatollah (Arabic āyat Allāh, “sign of God”). The honorific of grand ayatollah (āyat Allāh al-ʿuẓmāʾ) is conferred only upon those Shīʿite mujtahids whose level of insight and expertise in Islamic canon law has risen to the level of one who is worthy of being a marjaʿ-e taqlīd (Arabic marjaʿ al-taqlīd, “model of emulation”), the highest level of excellence in Iranian Shīʿism.

There is no real religious hierarchy or infrastructure within Shīʿism, and scholars often hold independent and varied views on political, social, and religious issues. Hence, these honorifics are not awarded but attained by scholars through general consensus and popular appeal. Shīʿites of every level defer to clergymen on the basis of their reputation for learning and judicial acumen, and the trend has become strong in modern Shīʿism for every believer, in order to avoid sin, to follow the teachings of his or her chosen marjaʿ-e taqlīd. This has increased the power of the ʿulamāʾ in Iran, and it has also enhanced their role as mediators to the divine in a way not seen in Sunni Islam or in earlier Shīʿism.

Religious minorities

Christians, Jews, and Zoroastrians are the most significant religious minorities. Christians are the most numerous group of these, Orthodox Armenians constituting the bulk. The Assyrians are Nestorian, Protestant, and Roman Catholic, as are a few converts from other ethnic groups. The Zoroastrians are largely concentrated in Yazd in central Iran, Kermān in the southeast, and Tehrān.

Religious toleration, one of the characteristics of Iran during the Pahlavi monarchy, came to an end with the Islamic revolution in 1979. While Christians, Jews, and Zoroastrians are recognized in the constitution of 1979 as official minorities, the revolutionary atmosphere in Iran was not conducive to equal treatment of non-Muslims. Among these, members of the Bahāʾī faith—a religion founded in Iran—were the victims of the greatest persecution. The Jewish population, which had been significant before 1979, emigrated in great numbers after the revolution.

Settlement patterns

Rural settlement





Urban settlement

cupola: mosque with cupola, Tehran, Iran [Credit: Margot Wolf—SCALA/Art Resource, New York]cupola: mosque with cupola, Tehran, IranMargot Wolf—SCALA/Art Resource, New YorkTehrān, the capital and largest city, is separated from the Caspian Sea by the Elburz Mountains. Eṣfahān, about 250 miles (400 km) south of Tehrān, is the second most important city and is famed for its architecture. There are few cities in central and eastern Iran, where water is scarce, although lines of oases penetrate the desert. Most towns are supplied with water by qanāt, an irrigation system by which an underground mountain water source is tapped and the water channeled down through a series of tunnels, sometimes 50 miles (80 km) in length, to the town level. Towns are, therefore, often located a short distance from the foot of a mountain. The essential feature of a traditional Iranian street is a small canal.



Demographic trends

Nearly one-fourth of Iranians are under 15 years of age. The country’s postrevolutionary boom in births has slowed substantially, and—with a birth rate slightly lower than the world average and a low death rate—Iran’s natural rate of increase is now only marginally higher than the world average. Life expectancy in Iran is some 68 years for men and 71 years for women.


Iran Flag


Supreme political/religious authorityLeader: Ayatollah Sayyed Ali Khamenei
Head of state and governmentPresident: Hassan Rouhani
Official languageFarsī (Persian)
Official religionIslam
Monetary unitrial (Rls)
Population(2014 est.) 77,555,000
Total area (sq mi)628,872
Total area (sq km)1,628,771
Urban-rural populationUrban: (2011) 69.1%
Rural: (2011) 30.9%
Life expectancy at birthMale: (2010) 70.9 years
Female: (2010) 74.7 years
Female: (2008) 77.2%
GNI per capita (U.S.$)(2013) 5,780
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