Iran, officially the Islamic
Republic of Iran, country in southwestern Asia, located on the
eastern shore of the
Persian Gulf. One of the world's most mountainous countries,
Iran contains
Mount Damāvand, the highest peak in Asia west of the
Himalayas. The country’s population, while ethnically and
linguistically diverse, is almost entirely Muslim. For
centuries, the region has been the center of the Shia branch of
Islam (see
Shia Islam). Iran ranks among the world’s leaders in its
reserves of oil and natural gas. As is the case in other
countries in the petroleum-rich Persian Gulf region, the export
of oil has dominated Iran’s economy since the early 20th
century.
In the 6th century
bc
the territory of present-day Iran was the center of the
Persian Empire, the world’s preeminent power at that time
. For more than 2,000 years, the region’s
inhabitants have referred to it by the name Iran, derived from
the Aryan tribes who settled the area long ago. However, until
1935, when the Iranian ruler demanded that the name Iran be
used, the English-speaking world knew the country as
Persia, a legacy of the Greeks who named the region after
its most important province, Pars (present-day Fārs). Iran was a
monarchy ruled by a shah, or king, from 1501 until 1979,
when a yearlong popular revolution led by the Shia clergy
culminated in the overthrow of the monarchy and the
establishment of an Islamic republic. See
Islamic Revolution of Iran.
Iran lies at the
easternmost edge of the geographic and cultural region known as
the
Middle East. The country is bordered on the north by
Armenia, Azerbaijan, the
Caspian Sea, and Turkmenistan; on the east by Afghanistan
and Pakistan; on the south by the
Gulf of Oman, the
Strait of Hormuz, and the Persian Gulf; and on the west by
Iraq and Turkey. Iran’s capital and largest city is
Tehrān, located in the northern part of the country.
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Iran is the second
largest country in the Middle East, after Saudi Arabia. It
extends over a total area of 1,648,000 sq km (636,300 sq mi).
The country is roughly triangular in shape, with its longest
side extending in a slightly outward arc for 2,500 km (1,600 mi)
from the border with Turkey in the northwest to the border with
Pakistan in the southeast. The third point of the triangle lies
in the northeast, about halfway along Iran’s border with
Turkmenistan. Iran’s greatest extent from north to south is
1,600 km (1,000 mi) and from east to west is 1,700 km (1,100
mi).
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Iran’s interior
plateaus are almost completely surrounded by mountains. The main
mountain system, the
Zagros Mountains, cuts across the country for more than
1,600 km (1,000 mi) from northwest to southeast. With the
exception of the Khūzestān coastal plain, which extends from the
northern reaches of the Persian Gulf, the Zagros Mountains
occupy all of western Iran. The central part of the range
averages more than 340 km (210 mi) in width. Many peaks of the
Zagros exceed 4,000 m (12,000 ft) in elevation; the highest is
Zard Kūh (4,547 m/14,918 ft). Peaks rising above 2,300 m (7,500
ft) capture considerable moisture, which percolates down to the
lower-lying basins as groundwater. These basins, ranging from
about 1,200 to 1,500 m (4,000 to 5,000 ft) in elevation, contain
fertile soil that traditionally has sustained diverse and
intensive crop cultivation.
In Iran’s northern
reaches, a steep, narrow mountain range, the
Elburz Mountains, rims the entire southern coast of the
Caspian Sea. This range extends more than 600 km (400 mi) in
length and averages about 100 km (about 60 mi) in width. The
country's highest peak, Mount Damāvand (5,670 m/18,602 ft), lies
in the central part of the range. Several other peaks of the
Elburz Mountains exceed 3,600 m (12,000 ft). The northern slopes
of the range receive considerable rainfall throughout the year
and support forests. A fertile coastal plain averaging 24 km (15
mi) in width lies between the Caspian Sea and the mountains.
East of the Elburz Mountains is a series of parallel mountain
ranges with elevations of 2,400 to 2,700 m (8,000 to 9,000 ft).
These ranges are interspersed with many narrow, arable valleys.
Several low mountain ridges, generally referred to as the
eastern highlands, run along Iran’s eastern border.
Within this mountainous
rim lies a series of basins known collectively as the central
plateau. They include the
Dasht-e Kavir, a huge salt-encrusted desert in north central
Iran; the
Dasht-e Lūt, a sand-and-pebble desert in the southeast; and
several fertile oases.
The mountains of Iran
constitute an active earthquake zone, and numerous minor
earthquakes occur each year. Major earthquakes causing great
loss of life and property damage also occur periodically. During
the 18th century earthquakes twice leveled Tabrīz, the principal
city in the northwest, killing at least 50,000 people on each
occasion. Several severe earthquakes resulting in 1,000 or more
deaths occurred during the second half of the 20th century. The
most devastating earthquake, centered in the fault zone where
the Elburz and Zagros mountains intersect, killed an estimated
40,000 people in June 1990. Several of Iran's highest mountains
are volcanic cones; only Mount Damāvand and Kūh-e Taftān in
southeastern Iran are active volcanoes, both periodically
emitting gases near their summits.
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Nearly all of Iran’s
numerous rivers are relatively short, shallow streams unsuitable
for navigation. The country’s only navigable river, the
Kārūn, flows through the city of
Ahvāz in the southwest. Most rivers rise in the mountainous
regions and drain into the interior basins. Since ancient times,
the region’s inhabitants have used the rivers for irrigation.
Dams constructed in the 20th century on the Āb-e Dez, Karkheh,
Karun, Sefid Rud, and other rivers have expanded the area under
irrigation and also have provided a principal source of
hydroelectricity. Three rivers form portions of Iran's
international boundaries. The Aras River lies along the border
with Armenia and Azerbaijan, the Atrek River borders
Turkmenistan, and the
Shatt al Arab is part of the border with Iraq. Iran also
shares the Caspian Sea, the world's largest inland body of
water, with four other countries. Several smaller saltwater
lakes lie entirely within Iran; the largest is
Lake Urmia in the northwest. A few small freshwater lakes
exist in high mountain valleys.
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More than half of
Iran's international border of 4,430 km (2,750 mi) is coastline,
including 740 km (460 mi) along the Caspian Sea in the north and
1,700 km (1,100 mi) along the Persian Gulf and adjacent Gulf of
Oman in the south. Both the Caspian Sea and the Persian Gulf
have important ports and contain extensive underwater deposits
of oil and natural gas. Iran's largest harbor, Bandar-e ‘Abbās,
is located on the Strait of Hormuz, the narrow passage
separating the Persian Gulf and the Gulf of Oman.
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Although more than
10,000 plant species have been identified in Iran, the natural
vegetation in most of the country has been uprooted and replaced
by cultivated crops or pastures. Natural forests consisting of
beech, oak, other deciduous trees, and conifers grow in parts of
the Elburz Mountains. Some regions of higher elevation in the
Zagros Mountains contain wooded areas consisting primarily of
oak. Wild fruit trees, including almond, pear, pomegranate, and
walnut, grow in both the Elburz and Zagros mountains. In the
more arid central part of the country, wild pistachio and other
drought-resistant trees grow in areas that have not been
disturbed by human activity. Tamarisk and other salt-tolerant
bushes grow along the margins of the Dasht-e Kavir.
A wide variety of
native mammals, reptiles, birds, and insects inhabit Iran. Many
species of mammals—including wolves, foxes, bears, mountain
goats, red mountain sheep, rabbits, and gerbils—continue to
thrive. Others—including Caspian tigers, Caspian seals, desert
onagers, three species of deer, gazelles, and lynx—are
endangered despite the establishment of special wildlife refuge
areas and other government programs initiated to protect them.
Some 502 species of birds inhabit Iran; more than 200 species
are migratory birds that spend part of the year in other
countries.
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Iran's extensive
petroleum and natural gas deposits are located primarily in the
southwestern province of Khūzestān and in the Persian Gulf. Iran
also has one of the world's largest reserves of copper; deposits
are located throughout the country, but the major lode lies in
the central region between the cities of
Yazd and
Kermān. This region also serves as a center for the mining
of bauxite, coal, iron ore, lead, and zinc. Additional coal
mines operate throughout the Elburz Mountains; iron ore mines
also exist near
Zanjān in the northwest, near
Mashhad in the northeast, and on Hormuz Island in the Strait
of Hormuz. Iran also has valuable deposits of aluminum, chromite,
gold, manganese, silver, tin, and tungsten, as well as various
gemstones, such as amber, agate, lapis lazuli, and turquoise.
Although about
one-third of Iran’s total land area is arable, only 10.7 percent
is under cultivation. An additional 6 percent of the total land
is used for pasture. Forested areas, found primarily in the
Elburz Mountains and the higher elevations of the Zagros
Mountains, have declined slightly in recent decades and account
for 4.5 percent of the total land area.
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Iran’s varied landscape
produces several different climates. On the northern edge of the
country, the Caspian coastal plain, with an average elevation at
or below sea level, remains humid all year. Winter temperatures
rarely fall below freezing, and maximum summer temperatures
rarely exceed 29° C (85° F). Annual precipitation averages 650
mm (26 in) in the eastern part of the plain (Māzandarān
Province) and more than 1,900 mm (75 in) in the western part (Gilān
Province).
At higher elevations to
the west, settlements in the Zagros Mountain basins experience
lower temperatures. These areas are subject to severe winters,
with average daily temperatures below freezing, and warm
summers, averaging 25° C (77° F) in the northwest and 33° C (91°
F) in the central and southern Zagros. Annual precipitation,
including snowfall, averages more than 280 mm (11 in) at higher
elevations. Most precipitation falls between October and April.
The central plateau
region also experiences regional variations. In Tehrān, located
at an elevation of 1,200 m (3,900 ft) on the northern edge of
the plateau, the temperature averages 2° C (36° F) in January
and 29° C (85° F) in July. The city receives an average of 230
mm (9 in) of precipitation annually. The arid basins of central
and eastern Iran generally receive less than 200 mm (8 in) of
precipitation per year. Yazd, for example, averages less than 70
mm (3 in) of precipitation. Its winters are cool, but
temperatures almost never fall below freezing; summers are very
hot, averaging 38° C (100° F) for most of July and August.
The coastal plains
along the Persian Gulf and the Gulf of Oman in southern Iran
have mild winters, with average January temperatures ranging
from 7° C to 18° C (45° F to 64° F) in Khūzestān Province;
average temperatures are even higher in Bandar-e ‘Abbās on the
Strait of Hormuz. Summers are very humid and hot, with
temperatures exceeding 48° C (119° F) during July in the
interior areas. Annual precipitation ranges from 145 mm to 355
mm (6 to 14 in) in this region.
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Iran's rapid
urbanization and industrialization have caused major
environmental problems. Air pollution, primarily from automobile
and factory emissions, has become a serious problem in Tehrān
and other large cities. A rising incidence of respiratory
illnesses prompted the city governments of Tehrān and
Arāk, southwest of the capital, to institute air pollution
control programs. These programs aim to reduce gradually the
amount of harmful chemicals released into the atmosphere.
Pollution of the Caspian Sea has increased substantially since
the early 1990s, reaching levels that threaten sturgeon and
other fish that sustain the Iranian fishing industry. Although
Iran enforces stringent controls on the dumping of municipal and
industrial wastes into Caspian waters within its territorial
limits, the other countries that border the Caspian Sea do not
control pollution in the northern two-thirds of the lake. Iran
has urged these countries to sign a binding international
agreement for cleaning up the Caspian Sea and preserving its
water quality.
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