The history of Iraq

Iraq covers most of ancient Mesopotamia, the land between the Tigris and Euphrates rivers, where the first cities, the first writing and the first empires appeared. Sumerians, Akkadians, Babylonians and Assyrians built successive civilisations there over three thousand years, before Persians, Greeks, Parthians and Sasanians ruled the land from outside. After the Arab conquest of the seventh century Iraq became a heartland of Islam, and under the Abbasid caliphs Baghdad was for a time the largest and most learned city in the world. Mongol, Turkmen, Persian and Ottoman rule followed, and in the twentieth century Britain drew the borders of a modern state that passed from monarchy to military republic, to the dictatorship of Saddam Hussein, and then through invasion, civil war and the rise and fall of the Islamic State.

The foothills of the Zagros Mountains in the north were inhabited long before the plains. Shanidar Cave in the Kurdish highlands held the remains of ten Neanderthals who lived there between about 65,000 and 35,000 years ago, some of them apparently buried with care. The same uplands lay within the arc where the Neolithic Revolution took place, and villages such as Jarmo, settled around 7000 BCE, were among the earliest farming communities anywhere, growing wheat and barley and herding goats and sheep.

Farming spread south onto the alluvial plain as people learned to channel river water into fields. The Hassuna, Samarra and Halaf cultures of the north produced fine painted pottery, and the Ubaid culture, named after a site near Ur and lasting from about 6500 to 3800 BCE, built the first temples at Eridu and dug irrigation canals across the south. Irrigation made the hot, nearly rainless plain extraordinarily fertile, but it also demanded organised labour and leadership, conditions in which the first cities would grow.

By the fourth millennium BCE Uruk had become the largest settlement on earth, with tens of thousands of inhabitants, monumental temples and a class of officials who managed grain, livestock and labour. Around 3200 BCE its scribes began pressing marks into clay tablets to keep accounts, and this system developed into cuneiform, a script later used for dozens of languages across the Near East. The people of the south, the Sumerians, also used the wheel, the plough and sexagesimal mathematics, from which the 60-minute hour descends.

Sumer was never a single kingdom. It was a land of rival city-states, including Uruk, Ur, Lagash, Umma, Kish and Nippur, each with its patron god and ruler, and they fought constantly over water and land. The royal tombs of Ur, from around 2600 BCE, were filled with gold, lapis lazuli and the bodies of attendants buried with their masters. Legends of Gilgamesh, a king of Uruk, grew into the Epic of Gilgamesh, one of the oldest surviving works of literature.

Around 2334 BCE Sargon of Akkad, a Semitic-speaking ruler from the north of the plain, conquered the Sumerian cities and created what is often called the first empire, reaching from the Persian Gulf towards the Mediterranean. Akkadian gradually replaced Sumerian as the spoken language, although Sumerian survived for centuries as a language of religion and learning. The Akkadian Empire collapsed in the twenty-second century BCE, and after a period of fragmentation the Third Dynasty of Ur revived Sumerian rule. Its founder Ur-Nammu began the great ziggurat of Ur and issued the oldest known law code, before Elamite invaders from Iran sacked Ur around 2004 BCE.

Amorite dynasties then took over many cities, among them Babylon, a minor town that Hammurabi made the capital of all southern Mesopotamia after he came to the throne in 1792 BCE. His law code, carved on a basalt stele, set out penalties that varied by social class and became the most famous legal text of the ancient world. In 1595 BCE the Hittites raided and sacked Babylon, and the Kassites, a people from the Zagros, ruled Babylonia for some four centuries, a long period of relative stability in which Babylon became the religious and cultural centre of the region.

In the north, the city of Assur on the Tigris was the heart of Assyria. Assyrian merchants of the early second millennium BCE ran a trading network deep into Anatolia, and from the fourteenth century BCE kings such as Ashur-uballit I turned Assyria into a major military power. After the upheavals of the Late Bronze Age collapse, when Aramaean tribes spread across Mesopotamia, the Neo-Assyrian Empire rose from 911 BCE to become the largest state the world had yet seen.

Its kings built ever grander capitals at Nimrud, Khorsabad and Nineveh, lined with carved stone reliefs of hunts and sieges. Tiglath-Pileser III, Sargon II and Sennacherib conquered Babylonia, the Levant and for a time Egypt, and deported whole populations to break resistance, including much of the northern kingdom of Israel. Ashurbanipal, who reigned from 669 to around 631 BCE, collected tens of thousands of tablets at Nineveh, a library that preserved much of Mesopotamian literature for modern scholars. Civil war weakened the empire after his death, and in 612 BCE a coalition of Babylonians and Medes sacked Nineveh. The last Assyrian resistance ended a few years later.

The victor of Nineveh, Nabopolassar, founded a new Babylonian dynasty, and his son Nebuchadnezzar II, who reigned from 605 to 562 BCE, made Babylon the greatest city of its age. He rebuilt it with massive walls, the blue-glazed Ishtar Gate and the ziggurat of Marduk, which may lie behind the biblical story of the Tower of Babel. The Hanging Gardens are traditionally attributed to him, although no trace of them has been confirmed. Nebuchadnezzar destroyed Jerusalem in 586 BCE and deported many of its people to Babylonia, the beginning of a Jewish community in Iraq that would last more than two and a half thousand years. The last Babylonian king, Nabonidus, spent years away in Arabia, and in 539 BCE Cyrus the Great took Babylon almost without a fight.

For the next twelve centuries Mesopotamia was ruled by empires based elsewhere, though it remained one of their richest provinces. Babylon was a royal residence of the Achaemenid Empire until Alexander the Great defeated Darius III at Gaugamela, near modern Erbil, in 331 BCE. Alexander planned to make Babylon his capital and died there in 323 BCE. Under the Seleucid Empire, the new Greek city of Seleucia on the Tigris drew people and trade away from Babylon, which slowly faded.

The Parthian Empire took Mesopotamia in the second century BCE and built its winter capital at Ctesiphon, across the river from Seleucia. Rome repeatedly fought the Parthians for the region, and the emperor Trajan briefly conquered it in 116 CE before his successor Hadrian gave it back. Cuneiform writing and the old temple religion died out in this era, the last known cuneiform tablets dating to the first century CE. In 224 the Sasanian Empire replaced the Parthians and kept Ctesiphon as its capital. Sasanian Iraq was religiously diverse: Zoroastrianism was the state faith, the Church of the East spread among Aramaic-speaking Christians, the Mandaeans practised their own baptismal religion, and the Jewish academies of Sura and Pumbedita compiled the Babylonian Talmud. Arab tribes settled along the desert edge, where the Lakhmid kings of al-Hira served as Sasanian clients, and the Persian name for the lowland, Erag, is one likely origin of the name Iraq.

Soon after the death of Muhammad, armies of the Rashidun Caliphate invaded Sasanian Iraq. After early setbacks, they won a decisive victory at al-Qadisiyyah around 636 and took Ctesiphon soon after. The conquerors founded garrison towns at Kufa and Basra, which grew into great cities, and Arabic and Islam spread slowly among a population that long remained largely Christian, Jewish and Zoroastrian, especially in the north.

Iraq was at the centre of the struggles that divided Islam. The fourth caliph, Ali, made Kufa his base and was assassinated there in 661, and in 680 his son Husayn was killed with a small band of followers at Karbala by forces of the Umayyad Caliphate. Ali's partisans became the Shia, and Najaf, where Ali is buried, and Karbala became the holiest Shia shrines. Under Umayyad rule from Damascus, Iraq was governed with a heavy hand by viceroys such as al-Hajjaj, and its discontent fed the revolution that toppled the dynasty in 750.

The Abbasid Caliphate moved the centre of the Islamic world to Iraq. In 762 the caliph al-Mansur founded Baghdad on the Tigris near the old Sasanian capital, laid out as a walled round city with the palace and great mosque at its heart. Within decades it was one of the largest cities in the world, possibly with more than a million inhabitants at its height, fed by the irrigated plain and trade reaching from China to Spain.

Under Harun al-Rashid, who ruled from 786 to 809, and his son al-Ma'mun, Baghdad became the centre of the Islamic Golden Age. Scholars associated with the House of Wisdom translated Greek, Persian and Indian works into Arabic, al-Khwarizmi wrote the treatise from which algebra takes its name, and al-Kindi pioneered Islamic philosophy. Basra and Kufa produced the grammarians and jurists who shaped Arabic and Islamic law. From 836 to 892 the caliphs ruled from a new capital at Samarra, whose spiral minaret still stands.

Political power drained away from the caliphs from the late ninth century. Turkish soldiers, provincial dynasties and finally the Persian Buyid dynasty, which took Baghdad in 945, controlled the caliphs, and in 1055 the Seljuk leader Tughril Beg entered the city and made the caliph a figurehead of the Seljuk Empire. The caliphs recovered some authority in Iraq in the twelfth century, but neglect of the canals and the salting of the soil were already eroding the prosperity of the south.

In 1258 the Mongol prince Hulagu, grandson of Genghis Khan, besieged Baghdad when the caliph al-Musta'sim refused to submit. The siege of Baghdad ended in a massacre whose death toll contemporaries put in the hundreds of thousands, the caliph was killed, and libraries including the House of Wisdom were destroyed. The Mongol Empire ended the Abbasid caliphate in Baghdad, and Iraq became a frontier province of the Ilkhanate ruled from Iran. The Black Death struck in the fourteenth century, and after the Ilkhanate broke up the Mongol Jalayirid dynasty ruled from Baghdad.

Tamerlane took Baghdad in 1393 and again in 1401, when much of its population was slaughtered. The Turkmen confederations of the Kara Koyunlu and then the Aq Qoyunlu ruled Iraq through the fifteenth century, and in 1508 Shah Ismail I brought it into the Safavid Empire of Iran, which promoted Shia Islam and venerated the shrines of Najaf and Karbala. Iraq had become a borderland between Persian and Turkish power, and its population, according to some estimates, was a small fraction of what it had been under the early Abbasids.

Suleiman the Magnificent captured Baghdad in 1534 and Basra soon after, bringing Iraq into the Ottoman Empire. The Safavids retook Baghdad in 1623, but Sultan Murad IV recovered it in 1638, and the Treaty of Zuhab of 1639 left most of what is now Iraq in Ottoman hands, drawing a frontier with Iran that survives in outline today. The land was divided into provinces centred on Baghdad, Basra, Mosul and Shahrizor in the Kurdish north, while tribal confederations held much of the countryside.

From the mid-eighteenth century a line of Mamluk pashas of mostly Georgian origin governed Baghdad with near independence, building an army and collecting revenue while recognising the sultan. In 1802 Wahhabi raiders from central Arabia sacked Karbala and killed thousands. The Ottomans overthrew the Mamluks in 1831 and imposed direct rule, and reforming governors, above all Midhat Pasha from 1869, introduced land registration, schools, newspapers and steamboats on the Tigris. Over the nineteenth century many southern tribes converted to Shia Islam, giving the south the Shia majority it has today, while Sunni Arabs predominated in the centre and Kurds in the mountains of the north.

The Ottomans joined World War I on Germany's side, and British and Indian troops landed near Basra in November 1914. A British army surrendered to the Ottomans at Kut in 1916, but Baghdad fell in March 1917 and Mosul was occupied after the armistice of 1918. In 1920 the League of Nations placed Iraq under a British mandate, and a large uprising by Shia tribes and nationalists that summer was suppressed with heavy losses. At the Cairo Conference of 1921, presided over by Winston Churchill, Britain chose the Hashemite prince Faisal, who had led the Arab revolt against the Ottomans, as king, and he was crowned in August 1921. The League awarded the oil-rich province of Mosul to Iraq in 1926, and a great oil strike at Kirkuk followed in 1927.

Iraq became formally independent and joined the League of Nations in 1932, though Britain kept air bases and strong influence. In 1933 the army massacred Assyrian Christian villagers at Simele. Faisal died the same year, and in 1936 Iraq experienced the first military coup in the modern Arab world. In 1941, during World War II, a pro-Axis government under Rashid Ali al-Gaylani took power, and Britain invaded and restored the regent; in the chaos of June 1941 a pogrom known as the Farhud killed more than a hundred Jews in Baghdad. After the founding of Israel, almost all of Iraq's ancient Jewish community, well over 100,000 people, left for Israel in 1950 and 1951. The monarchy, dominated by the veteran politician Nuri al-Said and aligned with the West through the Baghdad Pact of 1955, grew increasingly unpopular as Arab nationalism inspired by Gamal Abdel Nasser spread.

On 14 July 1958 army officers led by Abd al-Karim Qasim overthrew the monarchy; the young King Faisal II and much of the royal family were killed, and Nuri al-Said was killed the following day. Qasim's republic carried out land reform, left the Baghdad Pact and drew close to communists, but a Kurdish revolt led by Mustafa Barzani broke out in 1961 and his claim to Kuwait isolated him. In February 1963 the Arab nationalist Ba'ath Party and its army allies overthrew and executed Qasim, only to be pushed aside within months by Abd al-Salam Arif. A second Ba'athist coup in July 1968 brought Ahmed Hassan al-Bakr to power, with his relative Saddam Hussein as the regime's rising strongman.

The Ba'athist state nationalised the oil industry in 1972, and soaring oil revenues paid for roads, schools, hospitals and a vast security apparatus. War with the Kurds resumed in 1974 and ended when Iran stopped supporting the rebels under the Algiers Agreement of 1975. Saddam Hussein became president in July 1979 and immediately purged the party leadership. In September 1980 he invaded Iran, hoping to exploit the turmoil of its revolution. The Iran–Iraq War lasted until 1988, killing hundreds of thousands on both sides without changing the border. In its last phase the regime waged the Anfal campaign against the Kurds, destroying thousands of villages and killing tens of thousands of people; in March 1988 a chemical attack on the town of Halabja killed around 5,000 civilians.

Heavily indebted, Iraq invaded and annexed Kuwait in August 1990. A United States-led coalition authorised by the United Nations drove Iraqi forces out in the Gulf War of January and February 1991. Uprisings by Shia Arabs in the south and Kurds in the north were crushed, but Western no-fly zones allowed the Kurds to establish self-rule in the north. Through the 1990s, United Nations sanctions devastated the economy and public health, only partly eased by an oil-for-food programme from 1996, while inspectors searched for weapons of mass destruction.

Arguing that Iraq still held weapons of mass destruction and posed a threat after the attacks of 11 September 2001, the United States and Britain invaded in March 2003 without a new United Nations mandate. Baghdad fell on 9 April, and no stockpiles of such weapons were found. The American-led occupation authority dissolved the army and barred senior Ba'ath members from public life, decisions widely blamed for fuelling a Sunni Arab insurgency. Saddam Hussein was captured in December 2003 and hanged on 30 December 2006 after an Iraqi trial.

Iraqis voted in elections and approved a new federal constitution in October 2005, which recognised the Kurdistan Region and brought Shia parties to power. After the bombing of the al-Askari shrine in Samarra in February 2006, sectarian killing between Sunni and Shia militias, and attacks by al-Qaeda in Iraq, turned into civil war, killing tens of thousands of civilians and driving millions from their homes. Violence fell after 2007 with an American troop surge and the turn of Sunni tribal forces against al-Qaeda, and the last United States combat troops left in December 2011. The government of Prime Minister Nouri al-Maliki was accused by many Sunnis of sectarian rule, and protests in Sunni provinces in 2012 and 2013 were met with force.

From the end of 2013 the jihadist group known as ISIL or the Islamic State, which had grown out of al-Qaeda in Iraq and the Syrian civil war, seized towns in Anbar province. In June 2014 it captured Mosul, Iraq's second city, and Tikrit as the army collapsed, massacred up to 1,700 air force cadets at Camp Speicher, and on 29 June declared a caliphate under Abu Bakr al-Baghdadi spanning Iraq and Syria. In August 2014 its fighters attacked the Yazidis of Sinjar, killing thousands of men and enslaving thousands of women and children, crimes later recognised as genocide by the United Nations and many governments. Christians, Shia Turkmen and other minorities were also expelled or killed.

The Iraqi army, Shia volunteer militias of the Popular Mobilization Forces, Kurdish peshmerga and a United States-led air campaign gradually pushed the group back, retaking Tikrit in 2015, Ramadi at the end of that year and, after a nine-month battle, Mosul in July 2017. Prime Minister Haider al-Abadi declared victory on 9 December 2017. More than five million Iraqis had been displaced during the war. In September 2017 the Kurdistan Region voted overwhelmingly for independence in a referendum, and Baghdad responded by retaking Kirkuk and other disputed areas in October.

Iraq's post-war politics remained divided among Shia, Sunni and Kurdish parties sharing power by informal quota, and armed groups close to Iran gained strength. In October 2019 mass protests against corruption, unemployment and foreign interference, known as the Tishreen movement, spread across Baghdad and the south; security forces and militias killed hundreds of demonstrators, and Prime Minister Adil Abdul-Mahdi resigned. In January 2020 an American drone strike at Baghdad airport killed the Iranian general Qasem Soleimani and an Iraqi militia commander, deepening tension between Washington and Tehran on Iraqi soil. Mohammed Shia al-Sudani became prime minister in 2022 after a long stalemate following the 2021 election.

Parliamentary elections on 11 November 2025 left Sudani's coalition the largest single list, with 46 of 329 seats, but the Coordination Framework, an alliance of Shia parties, claimed the right to form a government. After months of deadlock, during which a nomination of the former prime minister Nouri al-Maliki was withdrawn, President Nizar Amedi named the banker Ali al-Zaidi as prime minister-designate in April 2026, and he was sworn in on 14 May with a partial cabinet. The regional war that began with American and Israeli strikes on Iran in February 2026 spilled onto Iraqi territory, with strikes against Iraqi militias aligned with Iran and attacks by Iran and its allies on targets in Iraq, including the Kurdistan Region. Iraq entered late 2026 still balancing between its American and Iranian partners.