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
Liao River million people. In 1958, the upriver of the Wailiao River at Liujianfang was blocked off via a river engineering project, redirecting the water flow from the Liao River "proper" entirely towards the Shuangtaizi River, effectively separating the Hun River and Taizi River from the main body of Liao River system. Therefore, since 1958, the Hun River and Taizi River were no longer considered tributaries of the Liao River, but an autonomous water system of their own. These following tributaries drain into the Liao River "proper" throughout its course within the Liaoning Province. Liao River The Liao River () is the