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
Water supply and sanitation in Iraq Tigris. The key structure is the Atatürk Dam on the Euphrates, which is located approximately 80 km upstream from the Syrian border. Turkey has stated that it would only guarantee a flow downstream from the dam of 15.75 km³/a (500 m³/s) of Euphrates water across the border to the Syrian Arab Republic. This represents about 50% of the natural flow of the Euphrates at the Turkish border. Both Syria and Iraq have tried to inhibit this. They stated that the minimum flow should average at least 700 m³/s but so far Turkey rejected this claim.(10) Syria is in the unusual