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 partitioned. Clause 109 of the treaty stipulated that the three riparian states of the Euphrates (at that time Turkey, France for its Syrian mandate and the United Kingdom for its mandate of Iraq) had to reach a mutual agreement on the use of its water and on the construction of any hydraulic installation. An agreement between Turkey and Iraq signed in 1946 required Turkey to report to Iraq on any hydraulic changes it made on the Tigris–Euphrates river system, and allowed Iraq to construct dams on Turkish territory to manage the flow of the Euphrates. The river featured on the