River, southeastern Iraq, formed by the confluence of the Euphrates rivers.
It flows southeastward for 120 mi (193 km) and passes the Iraqi port of Al- Basrah and the Iranian port of Ābādān before emptying into the Persian Gulf. With dredging, the river is navigable by shallow-draft oceangoing vessels. For about the last half of its course, the river forms the border between Iraq and Iran. In the 1980s it was the scene of prolonged fighting during the {{link=Iran-Iraq War">Iran-Iraq War .