The Tigris and Euphrates, with their tributaries, form a major river system in Western Asia. From sources in the Taurus mountains of eastern Turkey they flow by/through Syria through Iraq into the Persian Gulf.[5] The system is part of thePalearctic Tigris–Euphrates ecoregion, which includes Iraq and parts of Turkey, Syria, Iran, Saudi Arabia, Kuwait andJordan. 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.