Iran
Iran, officially the Islamic Republic of Iran, and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, Azerbaijan, and Armenia to the northwest, the Caspian Sea to the north, Turkmenistan to the northeast, Afghanistan to the east, Pakistan to the southeast, and the Gulf of Oman and the Persian Gulf to the south. With a population of over 90 million, Iran ranks 17th globally in both geographic size and population and is the sixth-largest country in Asia. It is divided into five regions with 31 provinces. Tehran is the nation's capital, largest city, and financial center.
Home to one of the world's oldest continuous major civilizations, most of Iran was first united as a nation by the Medes under Cyaxares in the 7th century BC and reached its territorial height in the 6th century BC, when Cyrus the Great founded the Achaemenid Empire. Alexander the Great conquered the empire in the 4th century BC. An Iranian rebellion in the 3rd century BC established the Parthian Empire, which later liberated the country. In the 3rd century CE, the Parthians were succeeded by the Sasanian Empire, which oversaw a golden age in the history of Iranian civilization. During this period, ancient Iran saw some of the earliest developments of writing, agriculture, urbanization, religion, and administration. Once a center for Zoroastrianism, Iran underwent Islamization following the 7th century CE Muslim conquest. Innovations in literature, philosophy, mathematics, medicine, astronomy and art were renewed during the Islamic Golden Age and Iranian Intermezzo, a period during which Iranian Muslim dynasties ended Arab rule and revived the Persian language. This era was followed by Seljuk and Khwarazmian rule, Mongol conquests and the Timurid Renaissance from the 11th to 14th centuries.
In the 16th century, the native Safavid dynasty re-established a unified Iranian state with Twelver Shia Islam as the official religion, laying the framework for the modern state of Iran. During the Afsharid Empire in the 18th century, Iran was a leading world power, but it lost this status after the Qajars took power in the 1790s. The early 20th century saw the Persian Constitutional Revolution and the establishment of the Pahlavi dynasty by Reza Shah, who ousted the last Qajar Shah in 1925. Following the Anglo-Soviet invasion of Iran in 1941, his son Mohammad Reza Pahlavi rose to power. Attempts by Mohammad Mosaddegh to nationalize the oil industry led to the Anglo-American coup in 1953. The Iranian Revolution in 1979 overthrew the monarchy, and the Islamic Republic of Iran was established by Ruhollah Khomeini, the country's first supreme leader. In 1980, Iraq invaded Iran, sparking the eight-year-long Iran–Iraq War, which ended in a stalemate. Iran has since been involved in proxy wars with Israel and Saudi Arabia; in 2025, Israeli strikes on Iran escalated tensions into the Iran–Israel war. Following the war and amid a growing economic crisis, potentially the largest protests since 1979 erupted in late December 2025.
Iran's government is an Islamic theocracy governed by elected and unelected institutions, with ultimate authority vested in the supreme leader. While it holds elections, key offices—including the head of state and military—are not subject to public vote. The Iranian government is an authoritarian regime which has been widely criticized internationally due to its poor human rights record, including restrictions on freedom of assembly, expression, and the press, as well as its treatment of women, ethnic minorities, and political dissidents. International observers have raised concerns over the fairness of its electoral processes, especially the vetting of candidates by unelected bodies such as the Guardian Council. Iran maintains a centrally planned economy with significant state ownership in key sectors, though private enterprise exists alongside this. It is a middle power, due to its large reserves of fossil fuels, its geopolitically significant location, and its role as the world's focal point of Shia Islam. Iran is a threshold state with one of the most scrutinized nuclear programs, which it claims is solely for civilian purposes; however, the IAEA, a UN agency tasked with monitoring the production of nuclear weapons, has on two occasions found Iran to be non-compliant with its safeguards obligations. It is a founding member of the United Nations and a member state of numerous international organisations. Iran has 29 UNESCO World Heritage Sites and ranks 4th in intangible cultural heritage or human treasures.
Name
History
Prehistory
The earliest known presence of hominins in Iran dates to around 800,000 BP, in the Middle Paleolithic. Many Middle Paleolithic sites have been discovered, mainly in the Zagros Mountains in western Iran and some sites associated with Neanderthals. The Zarzian culture is documented in Iran during the Epipaleolithic. Agriculture first appeared in Iran some 12,000 years ago alongside better-documented settlements in the Fertile Crescent. The Chogha Golan site featured early domestication of emmer wheat, The contemporary site of Ganj Dareh also features the earliest known domestication of goats around 10,000 years ago.The ancient city of Susa, which would become the capital of Elam and later a capital city of the Achaemenid empire, was first settled in 4400–4200 BC, adjacent to the modern site of Shush, Iran. The Kura–Araxes culture existed in northwestern Iran and the Caucasus.
Antiquity
Iran is home to one of the world's oldest continuous major civilizations, with historical and urban settlements dating back to 4000 BC, including the Jiroft culture in southeastern Iran. Inscriptions in the Proto-Elamite script, which predates cuneiform, have been found from the early third millennium BC. The western part of the Iranian plateau participated in the traditional ancient Near East with Elam, and later with other peoples such as the Kassites, Mannaeans, and Gutians. The earliest Iranian peoples began to arrive from Central Asia in the 2nd millennium BCE.The Median dynasty ruled the earliest Iranian state. In 612 BC, Cyaxares and the Babylonian king Nabopolassar invaded Assyria and destroyed Nineveh, the Assyrian capital, which led to the fall of the Neo-Assyrian Empire. The Medes later conquered and dissolved Urartu as well.
Achaemenid Empire
The Achaemenids united all Persian tribes under Cambyses I. Under his son, Cyrus the Great, the Achaemenids defeated the Medes and established the Achaemenid Empire, the largest-ever Iranian state. Cyrus conquered the Lydian and Neo-Babylonian empires, creating an empire far larger than Assyria. His son, Cambyses II, conquered the last major power of the region, ancient Egypt, causing the collapse of its twenty-sixth dynasty.After the death of Cambyses II, Darius the Great ascended the throne by overthrowing the Achaemenid monarch Bardiya. Darius' first capital was at Susa, and he started the building program at Persepolis. He improved the extensive road system, and during his reign the first recorded mentions are made of the Royal Road, a highway from Susa to Sardis.
In 499 BC, Athens supported a revolt in Miletus, resulting in the sacking of Sardis. This led to the Greco-Persian Wars, which lasted the first half of the 5th century BC. In the First Persian invasion of Greece, Persian general Mardonius re-subjugated Thrace and made Macedon a full part of Persia. Darius' successor Xerxes I launched the Second Persian invasion of Greece. At a crucial moment in the war, about half of mainland Greece was overrun by the Persians, including territories to the north of the Isthmus of Corinth. This was reversed by a Greek victory following the battles of Plataea and Salamis, during which Persia lost its footholds in Europe, and withdrew from it.
The empire entered a period of decline. From 334 BC to 331 BC, Alexander the Great defeated Darius III in the battles of Granicus, Issus and Gaugamela, swiftly conquering the Achaemanid Empire by 331 BC. Alexander's empire collapsed after his death; his general, Seleucus I Nicator, tried to take control of Iran, Mesopotamia, Syria, and Anatolia. His empire was the Seleucid Empire.
Parthian and Sasanian empires
The Arsacids of Parthia, initially Seleucid vassals, originated as leaders of the Iranian Parni tribe in the northeastern steppes. The Parthians gradually challenged Seleucid rule over Iran, eventually securing control through the 142 BC conquest of Babylonia. Although fighting continued, the death of Antiochus VII Sidetes in 129 BC marked the collapse of the Seleucid Empire, which then lingered on as a rump state in Syria until conquered by the Roman Empire in the 60s BC.File:The Sasanian Empire at its apex under Khosrow II.svg|thumb|upright=1.3|The Sasanian Empire at its greatest extent, under the reign of Khosrow II
The Parthian Empire endured for five centuries, but civil wars destabilized it. Parthian power evaporated when Ardashir I revolted against the Arsacids and killed their last ruler, Artabanus IV, in 224 AD. Ardashir established the Sasanian Empire, which ruled Iran and much of Near East before the Muslim conquests of the 7th century AD.
At their zenith, the Sasanians controlled all of modern-day Iran and Iraq and parts of the Arabian Peninsula, as well as the Caucasus, the Levant, and parts of Central and South Asia. The strong economic conditions left by Parthians allowed the Sasanians to build a powerful and distinctive economic state whose reputation spread well beyond its political frontiers and time. The Sasanian Empire was characterized by a complex and centralized government bureaucracy and the revitalization of Zoroastrianism as a legitimizing and unifying ideal.