Tigris–Euphrates river system through the central plain and combine at Al-Qurnah to form the Shatt al-Arab and discharge into the Persian Gulf. The region has historical importance as part of the Fertile Crescent region, in which civilization is believed to have first emerged. The ecoregion is characterized by two large rivers, the Tigris and Euphrates. The rivers have several small tributaries which feed into the system from shallow freshwater lakes, swamps, and marshes, all surrounded by desert. The hydrology of these vast marshes is extremely important to the ecology of the entire upper Persian Gulf. Historically, the area is known as Mesopotamia. As
Euphrates coat of arms of Iraq from 1932-1959. Turkey and Syria completed their first dams on the Euphrates – the Keban Dam and the Tabqa Dam, respectively – within one year of each other and filling of the reservoirs commenced in 1975. At the same time, the area was hit by severe drought and river flow toward Iraq was reduced from in 1973 to in 1975. This led to an international crisis during which Iraq threatened to bomb the Tabqa Dam. An agreement was eventually reached between Syria and Iraq after intervention by Saudi Arabia and the Soviet Union. A similar