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
Operation Euphrates Shield Operation Euphrates Shield Operation "Euphrates Shield" () was a cross-border operation by the Turkish military and Turkey-aligned Syrian opposition groups in the Syrian Civil War which led to the Turkish occupation of northern Syria. Operations were carried out in the region between the Euphrates river to the east and the rebel-held area around Azaz to the west. The Turkish military and Turkey-aligned Syrian rebel groups, some of which used the Free Syrian Army label, fought against forces of the Islamic State of Iraq and the Levant (ISIL) as well as against the Syrian Democratic Forces (SDF) from 24 August 2016.