Modern Iraq includes the territory known in ancient times as Mesopotamia. This region, consisting of the land between the Tigris and Euphrates rivers, was one of the first centers of civilization. The Sumerians, Akkadians, Babylonians, Assyrians, and Chaldeans established great empires in this area.

Important dates in Iraq
3500 B.C. The world's first known civilization developed in Mesopotamia, now Iraq.
539 B.C. The Persians conquered Mesopotamia.
331 B.C. Alexander the Great seized Mesopotamia.
c. A.D. 224 The Sasanian dynasty of Persia conquered Mesopotamia.
637 Arab Muslims overthrew the Sasanians.
1258 The Mongols invaded Mesopotamia.
1500's The Ottoman Empire began to establish control over Mesopotamia.
1920 The League of Nations gave the United Kingdoma mandate (order to rule) over Mesopotamia.
1932 The British mandate ended, and Iraq became independent.
1958 Army officers overthrew the Iraqi government and declared the country a republic.
1968 The Baath Party took control of Iraq's government.
1973 The Iraqi government completed its take-over of foreign oil companies in Iraq.
1980 Iraq declared war on Iran.
1988 Iraq and Iran agreed to a cease-fire.
1990 Iraq invaded Kuwait.
1991 A coalition of 39 nations, organized mainly by the United Nations and the United States, defeated Iraq in the Persian Gulf War of 1991.
2003 Forces led by the United States overthrew the Baath Party government of Saddam Hussein in the Iraq War.
2005 Iraqis elected a permanent government under their new constitution.

In 539 B.C. Cyrus the Great conquered Mesopotamia for the Persian Empire. Alexander the Great's conquest in 331 B.C. led to the rule of the Seleucids, a Macedonian dynasty. Later the region was ruled by two Persian dynasties; the Parthians ruled from 130 B.C. to 226 A.D. , and the Sassanids ruled from 226 to 640.

Mesopotamia was conquered by Arabs about 640, and its people became Arabic-speaking Muslims. Under the Abbasid Caliphate, 750–1258, the region enjoyed great prosperity. After repeated devastation by Mongols, Turks, and Persians, however, Mesopotamia's economy was ruined. The Ottoman Turks gained permanent possession of the area in 1638.