Iraq is a country located in the Middle East. The region was called Mesopotamia by the ancient Greeks, and it was here that civilization is thought to have originated. The first states in the region were the Sumerian city-states, which arose in the 4th millennium BCE. The first of these was Uruk, which is thought to be the world's first city.Iraq was conquered by the Assyrians in the 8th century BCE, and it became a province of the Persian Empire in the 6th century BCE. Alexander the Great conquered the Persians in the 4th century BCE, and after his death, the region became part of the Hellenistic Seleucid Empire.In the 2nd century BCE, the Parthians conquered the Seleucids and established their own empire, which included present-day Iraq. The Parthians were eventually supplanted by the Sassanids, who ruled the region until the 7th century CE.Iraq was conquered by the Arabs in the 7th century CE, and it became a province of the Umayyad Caliphate. The Abbasid Caliphate, which overthrew the Umayyads, also ruled Iraq. The Mongols conquered Iraq in the 13th century CE, and it became part of the Ilkhanate.Iraq was under Ottoman rule from the 16th century CE until the 20th century CE. The British conquered Iraq in the First World War, and it became a League of Nations mandate. Iraq gained independence in 1932, but it was annexed by the United Kingdom in 1941 during the Second World War.Iraq was declared a republic in 1958, and Saddam Hussein became president in 1979. Saddam Hussein's regime was overthrown by the United States-led coalition in the 2003 Iraq War. Iraq has been governed by a series of interim governments since then, and it is currently in the process of formulating a new constitution.