Iran

• 1. Introduction

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  Iran sits on one of the world's oldest continuous major civilizations, and the people of present-day Iran were first unified under the Medes in the 7th century BC. Officially the Islamic Republic of Iran, historically known as Persia, it is a country in West Asia with a population of over 92 million. It ranks 17th globally in both geographic size and population. Its borders touch Iraq, Turkey, Azerbaijan, Armenia, Turkmenistan, Afghanistan, Pakistan, and the waters of the Caspian Sea, the Gulf of Oman, and the Persian Gulf.

  Tehran, the capital and largest city, is the nation's primary economic centre. But a capital tells you little about a land where hominins lived around 800,000 years ago, where goats were first domesticated near Ganj Dareh some 10,000 years ago. How does a country move from the Achaemenid Empire of Cyrus the Great to a theocratic republic whose supreme leader holds ultimate authority? What turned a Zoroastrian heartland into the world's focal point of Shia Islam? And how did a nation with 10% of the world's oil reserves arrive at a nuclear program among the most scrutinized on earth? The answers run through empires, revolutions, and a system of power unlike almost any other.

• 2. Empires Of The Plateau

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  Cyrus the Great founded the Achaemenid Empire, the largest-ever Iranian state, after the Achaemenids defeated the Medes. His son Cambyses II, who ruled from 530 to 522 BC, conquered ancient Egypt and collapsed its twenty-sixth dynasty. The empire reached its territorial height in the 6th century BC.

  Darius the Great, who ruled from 522 to 486 BC, ascended by overthrowing the monarch Bardiya. He made his first capital at Susa and began building Persepolis. Under Darius came the first recorded mentions of the Royal Road, a highway stretching from Susa to Sardis. His successor Xerxes I launched the Second Persian invasion of Greece, but Greek victories at Plataea and Salamis stripped Persia of its footholds in Europe.

  From 334 BC to 331 BC, Alexander the Great defeated Darius III at the battles of Granicus, Issus, and Gaugamela. The Achaemenid Empire fell by 331 BC. After Alexander died, his general Seleucus I Nicator built the Seleucid Empire across Iran, Mesopotamia, Syria, and Anatolia.

  The Arsacids of Parthia began as Seleucid vassals and leaders of the Iranian Parni tribe. They secured control through the 142 BC conquest of Babylonia, and their empire endured for five centuries. Parthian power ended when Ardashir I revolted and killed the last Arsacid ruler, Artabanus IV, in 224 AD. Ardashir established the Sasanian Empire, which at its zenith controlled all of modern-day Iran and Iraq and parts of the Arabian Peninsula, the Caucasus, the Levant, and Central and South Asia. The Sasanians revitalized Zoroastrianism as a unifying ideal, a faith that would soon face a profound challenge from the west.

• 3. Islam And The Persian Revival

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  The Rashidun Caliphate conquered the Sasanian Empire between 632 and 654, and over time most Iranians converted to Islam. Yet most aspects of earlier Persian civilization were absorbed rather than discarded. Middle Persian remained the language of official business in the caliphate until Arabic was adopted toward the end of the seventh century.

  Iran was not entirely under Arab control. The Daylam region answered to the Daylamites, Tabaristan to the Dabuyid and Paduspanid rulers, and Mount Damavand to the Masmughan. Farrukhan the Great, the most prominent Dabuyid ruler from 712 to 728, held his domains against the Arab general Yazid ibn al-Muhallab, who was forced to retreat from Tabaristan.

  In 747 to 750, an insurrection grew into the Abbasid revolution, replacing the Umayyads with the Abbasids, descendants of Muhammad's uncle Abbas. As Abbasid authority waned across the 9th and 10th centuries, independent Iranian dynasties rose. This stretch, until the Seljuk conquest of the 11th century, is called the Iranian Intermezzo. The Tahirids ruled Khorasan, the Saffarids held Sistan, and the Samanids governed from Bukhara to Pakistan.

  Seyyed Hossein Nasr, a historian, suggests the rapid rise in conversions was aided by the Persian nationality of the rulers. The Muslim population climbed from roughly 40% in the mid-9th century to nearly 90% by the end of the 11th. Even as Persians adopted their conquerors' religion, they revived their distinctive language and culture, a process known as Persianization in which Arabs and Turks also took part.

• 4. Conquest And Renaissance

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  Bukhara fell to the Mongols in 1220, and the Khwarazmian Empire was destroyed. During 1220 to 1221, Bukhara, Samarkand, Herat, Tus, and Nishapur were razed and their whole populations slaughtered. The conquests culminated in the fall of Baghdad and the end of Abbasid rule in 1258.

  Hulegu Khan took power across much of the empire's southwest, including Iran, and was legitimized through a fatwa issued by the Shia scholar Ali ibn Tawus al-Hilli. Iran experienced a cultural renaissance under Ilkhanid rule. Ghazan Khan converted to Islam in the late 13th century, turning the state away from the other Mongol realms. After his nephew Abu Said died in 1335, the Ilkhanate lapsed into civil war among petty dynasties including the Jalayirids and Muzaffarids. The mid-14th-century Black Death killed about 30% of the country's population.

  Timur, who ruled from 1370 to 1405, founded the Persianate Timurid dynasty and hailed from a Turkified tribe of Mongols. He invaded Iran in 1381 and conquered most of it with notorious brutality. In 1387 he ordered the complete massacre of Isfahan, killing 70,000 people. The Timurids held Iran until 1452, when they lost most of it to the Qara Qoyunlu, who were in turn conquered by the Aq Qoyunlu in 1468. Uzun Hasan and his successors mastered Iran until a new native power arose to reunify it under a single faith.

• 5. The Safavid Foundation

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  Ismail I, who ruled from 1505 to 1524, founded the Safavid Empire, often considered the beginning of modern Iranian history. The Safavids reunified Iran as a cohesive entity under native rule and established Shia Islam as the official religion. Twelver Shia Islam became the framework for the modern state.

  The Safavid shah was legitimized by his bloodline as a sayyid, a descendant of Muhammad. He monitored officials through reports from the superintendent of each department, a bureaucratic system of checks and balances designed not to equalize power but to ensure the total power of the shah. Jean Chardin, a French merchant who became ambassador to Iran, wrote that the Safavid shahs ruled with an iron fist and often in a despotic manner.

  The Safavids ruled from 1501 to 1722, with a brief restoration from 1729 to 1736. Their empire collapsed after the siege of Isfahan in 1722, when the Afghan Hotak dynasty invaded. The turmoil that followed opened the door for rival commanders, one of whom would build an empire spanning a dozen modern nations.

• 6. Conquerors And Dynasties

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  Nader Shah, who ruled from 1736 to 1747, has been described as the last great Asiatic military conqueror and compared to Napoleon and Alexander the Great. His campaigns briefly built an empire reaching across all or part of Afghanistan, Armenia, Azerbaijan, Bahrain, Georgia, India, Iraq, Turkey, Oman, Pakistan, Uzbekistan, the North Caucasus, and the Persian Gulf. His military spending had a ruinous effect on the Iranian economy.

  The Zand family seized control of much of Iran in the 1750s under Karim Khan, who ruled from 1751 to 1779. The Zand rulers never proclaimed themselves shahs, calling themselves regents instead, first on behalf of the Safavid puppet Ismail III and then on behalf of the Iranian people.

  Agha Mohammad Shah proclaimed himself ruler in 1789, defeated the Zand dynasty in 1794, and was crowned in 1796. He captured the Afsharid Shahrokh Shah and reunified Iran under one ruler. In the 19th century, Iran lost significant territories in the Caucasus to the Russian Empire after the Russo-Persian Wars, while Britain pushed into the south to counter Russia near British India. Drought, shifting agriculture, and poor governance brought the Great Persian Famine of 1870 to 1871, which killed between several hundred thousand and four million Iranians.

• 7. From Shah To Republic

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  The Persian Constitutional Revolution between 1905 and 1911 established an Iranian parliament. After the 1921 coup, Reza Shah replaced the Qajar dynasty and founded the Pahlavi line, building an authoritarian government rooted in nationalism, militarism, secularism, and strict censorship. Supporters credited him with law and order and modern amenities like schools, trains, buses, radios, cinemas, and telephones. He ruled almost 16 years until the Anglo-Soviet invasion forced his abdication in 1941.

  Iran rejected Allied demands to expel German residents, so Britain and the Soviet Union invaded in August 1941 in Operation Countenance. Iran became the major conduit of Allied Lend-Lease aid to the Soviet Union through the Persian Corridor while remaining officially neutral. Reza Shah was deposed and replaced by his young son Mohammad Reza Pahlavi. At the 1943 Tehran Conference, the Big Three of Stalin, Roosevelt, and Churchill issued the Tehran Declaration guaranteeing Iran's post-war independence.

  In 1951, under Prime Minister Mohammad Mosaddegh, parliament voted to nationalize the British-owned oil industry, triggering the Abadan Crisis. On the 19th of August 1953, a coup led by retired general Fazlollah Zahedi, aided by the US CIA and British MI6 and known as Operation Ajax, forced Mosaddegh from office. He was tried for treason and placed under house arrest, while his foreign minister Hossein Fatemi was executed.

  The Shah then ruled as an autocrat with strong American support, launching reforms known as the White Revolution. By 1978 he had become wildly unpopular. When protestors persisted, security forces opened fire in an incident known as Black Friday. The protests grew to include more than 10% of the country, a scale rare for any revolution.

• 8. The Islamic Republic

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  On the 31st of March 1979, a referendum on transitioning from monarchy to an Islamic republic was approved by a margin of 99.31%. Ayatollah Ruhollah Khomeini became Supreme Leader in December 1979, replacing the capitalist economy with populist Islamic policies. On the 4th of November 1979, Iranian students seized US embassy personnel and held 52 hostages for 444 days until January 1981.

  On the 22nd of September 1980, the Iraqi army invaded Iran at Khuzestan under Saddam Hussein, beginning the Iran-Iraq War. Iranian forces pushed Iraq back by 1982, but the war ground on until 1988, when Khomeini said he drank the cup of poison and accepted a UN truce. It killed approximately 500,000 people, and Saddam used chemical weapons against Iranians.

  On his deathbed in 1989, Khomeini appointed a 25-man council that named Ali Khamenei as the next Supreme Leader. Power in the republic rests ultimately with the Supreme Leader, the Rahbar, who commands the armed forces, appoints the heads of the judiciary and the Guardian Council, and can order laws amended. The president is elected by universal suffrage for four years, but candidates must first be approved by the 12-member Guardian Council. The Assembly of Experts elects the Rahbar yet has never challenged his decisions. The legislature, the 290-member Majles, cannot pass laws without Guardian Council approval.

  The nuclear program, dating to the 1950s, became the heart of international negotiation. In 2015 the Joint Comprehensive Plan of Action was reached in Vienna between Iran, the P5+1, and the EU, trading sanctions relief for limits on enriched uranium. In 2018 the US under Donald Trump withdrew, and Iran advanced toward nuclear threshold status, enriching uranium up to 60% fissile content.

  In early 2025 Iran rapidly advanced its program. On the 13th of June 2025, Israel launched strikes across Iran, the US struck nuclear facilities on the 22nd of June, and a ceasefire was agreed on the 24th of June. From December 2025, mass demonstrations demanded the overthrow of the Islamic Republic. On the 28th of February 2026, the United States and Israel conducted coordinated strikes, and Ali Khamenei was assassinated, his death confirmed on the 1st of March. On the 8th of March, the 88-person Assembly of Experts announced that Mojtaba Khamenei, his son, was elected Supreme Leader in what it called a unanimous vote.