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
Khabur (Euphrates) Khabur (Euphrates) The Khabur River ( ', , ', , - Chaboras, Aborrhas, or Abura, ) is the largest perennial tributary to the Euphrates in Syrian territory. Although the Khabur originates in Turkey, the karstic springs around Ra's al-'Ayn are the river's main source of water. Several important wadis join the Khabur north of Al-Hasakah, together creating what is known as the Khabur Triangle, or Upper Khabur area. From north to south, annual rainfall in the Khabur basin decreases from over 400 mm to less than 200 mm, making the river a vital water source for agriculture throughout history. The