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 unrecorded substrate language. Tamaz V. Gamkrelidze and Vyacheslav Ivanov suggest the Proto-Sumerian *burudu "copper" (Sumerian "urudu") as an origin, with an explanation that Euphrates was the river by which the copper ore was transported in rafts, since Mesopotamia was the center of copper metallurgy during the period. The earliest references to the Euphrates come from cuneiform texts found in Shuruppak and pre-Sargonic Nippur in southern Iraq and date to the mid-3rd millennium BCE. In these texts, written in Sumerian, the Euphrates is called "Buranuna" (logographic: UD.KIB.NUN). The name could also be written KIB.NUN.(NA) or KIB.NUN, with the prefix "" indicating