<P> From their sources and upper courses in the mountains of eastern Anatolia, the rivers descend through valleys and gorges to the uplands of Syria and northern Iraq and then to the alluvial plain of central Iraq . The rivers flow in a south - easterly direction through the central plain and combine at Al - Qurnah to form the Shatt al - Arab and discharge into the Persian Gulf . </P> <P> The region has historical importance as part of the Fertile Crescent region, in which civilization is believed to have first emerged . </P> <P> 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 part of the larger Fertile Crescent, it saw the earliest emergence of literate urban civilization in the Uruk period, for which reason it is often described as a "Cradle of Civilization". </P> <P> In the 1980s, this ecoregion was put in grave danger as the Iran--Iraq War raged within its boundaries . The wetlands of Iraq, which were inhabited by the Marsh Arabs, were almost completely dried out, and have only recently shown signs of recovery . </P>

The area between the tigris and euphrates rivers is referred to as what ​​​​
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