A hotbed of Arab nationalism after achieving independence from Britain in 1932, it has a history of conflict with its neighbours and the wider world.
Its 1980-88 war with Shi'ite Muslim neighbour Iran killed hundreds of thousands of people and became the Middle East's longest and bloodiest modern conflict.
Saddam Hussein, who took power in 1979 after a decade as Iraq's strongman, survived the 1991 Gulf War and Shi'ite and Kurdish uprisings that followed his invasion of Kuwait.
Accused by the United States and Britain of hiding banned weapons of mass destruction, he now faces the threat of a third major war in as many decades.
These are the key facts on Iraq:
POPULATION: Official estimate is 24 million. Arabic is the official languageA Kurdish minority of 16% lives in the northeast region near Turkey.
RELIGION: Predominantly Islam. Shi'ites form a majority but Sunni Muslims have traditionally ruled the country.
AREA: 434,924 square km (167,925 square miles)
NEIGHBOURS: Iran (east), Saudi Arabia and Kuwait (south), Jordan and Syria (west), Turkey (north). Iraq also has a short stretch of Gulf coast next to Kuwait in the southeast.
CAPITAL: Baghdad; population around five million.
ARMED FORCES: Army 350,000 men, 2,600 tanks; air force 20,000 men, 316 combat aircraft; navy 2,000 men, six patrol and coastal craft, six mine warfare vessels; air defence command 17,000 men; paramilitary forces 15,000 security troops, 9,000 border guards, 18,000-20,000 Saddam's Fedayeen. ECONOMY: Oil Iraq's proven reserves of 112 billion barrels are second only to Saudi Arabia's. Other industries include mining, gas, construction, fishing, forestry and agriculture.
GDP $11.5 billion in 1996, down 15% from 1995. In 1985, GDP was $46.8bn. Iraq's total external debt in mid-1989 was estimated at around $65bn.
Iraq had a trade surplus of $1.6bn in 1987. It stood at $300m in 1996.
HISTORY: Known as Mesopotamia or the land between the rivers, modern Iraq was home to a string of ancient empires. The Sumerians, credited with creating the art of writing and brewing, and formalising agriculture, ruled from 4000 BC before Babylonians, Assyrians, Persians and Arabs all left their mark.
Turkey's Ottomans absorbed the region in the 16th century and ruled until World War One, when it came under British rule.
Iraq won full independence from Britain in 1932. Nationalist army officers toppled the monarchy in 1958.
The Sunni-dominated Baath Party took power in a 1968 coup. Having previously held the position of vice-president of the Revolutionary Command Council, Saddam Hussein becomes president of Iraq in 1979. Iraq invaded Iran in 1980. The first Gulf War ended in 1988 with a ceasefire.
Iraq invaded Kuwait in 1990, accusing it of stealing its oil. The United Nations imposed trade sanctions.
A US-led coalition ejected Iraqi forces in 1991 in a second Gulf War. The UN Security Council ordered Iraq to scrap all its weapons of mass destruction and sent in arms inspectors. Iraq resumed limited exports in 1996 under an oil-for-food deal. Citing lack of cooperation, UN weapons inspectors pulled out in 1998.
In 2002, US President George W Bush dubbed Iraq a member of an "axis of evil" developing weapons of mass destruction. In November, the Security Council unanimously gave Iraq one last chance to disarm or face "serious consequences". Iraq let UN inspectors return without conditions.
Diplomatic wrangling split the Security Council in 2003, with the US and Britain accusing Saddam of hiding weapons of mass destruction and pushing for a final disarmament ultimatum backed by the threat of war. Iraq denies it has illegal weapons.