The Tigris–Euphrates river system is a large river system in Western Asia that discharges into the Persian Gulf. Its principal rivers are the Tigris and Euphrates, along with smaller tributaries.

The Tigris is the eastern of the two great rivers that define Mesopotamia, the other being the Euphrates. The river flows south from the mountains of the Taurus in Turkey, then through the Syrian and Arabian Deserts, emptying into the Persian Gulf.