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
Sharing the water of the Ganges arrangement and recognised Bangladesh's rights as a lower-level riparian. Descending from India's northern plains, the Ganges river forms a boundary of 129 kilometres between India and Bangladesh and flows for 113 km in Bangladesh. At Pakaur in India, the river begins its attrition with the branching away of its first distributary, the Bhagirathi River, which goes on to form the Hooghly River. About 10 kilometres from the border with Bangladesh the Farakka Barrage, built in 1974, controls the flow of the Ganges, diverting some of the water into a feeder canal linking the Hooghly to keep it relatively silt-free. After