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 of Southeast Turkey. The presence of European beaver has been attested in the bone assemblage of the prehistoric site of Abu Hureyra in Syria, but the beaver has never been sighted in historical times. The Hindiya Barrage on the Iraqi Euphrates, based on plans by British civil engineer William Willcocks and finished in 1913, was the first modern water diversion structure built in the Tigris–Euphrates river system. The Hindiya Barrage was followed in the 1950s by the Ramadi Barrage and the nearby Abu Dibbis Regulator, which serve to regulate the flow regime of the Euphrates and to discharge excess flood