The Tigris-Euphrates river system is part of the Tigris-Euphrates alluvial salt marsh ecoregion of the Middle East, and is characterized by two large rivers, the Tigris and Euphrates. The rivers have several small tributaries which feed into 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, in an area called the Cradle of Civilization due to its ancient history.
In the 1980s this ecoregion was put in grave danger as the Iran–Iraq War raged within its boundaries. It also faced one of the massive economic-environmental crimes in modern history: the destruction of Iraq's wetlands.
Marshlands were a fine and extensive natural wetlands ecosystem. They developed over thousands of years in the Tigris-Euphrates basin and once covered 15–20,000 square kilometers. According to the United Nations Environmental Program and the AMAR Charitable Foundation, between 84% and 90% of the marshes have been destroyed since the 70s. In 1994, 60 percent of the wetlands were destroyed by Saddam Hussein's regime. They were drained to permit military access and greater political control of the native Marsh Arabs. Canals, dykes and dams were built routing the water of the Tigris and Euphrates Rivers around the marshes, instead of allowing water to move slowly through the marshland. After part of the Euphrates was dried up due to re-routing its water to the sea, a dam was built so water could not back up from the Tigris and sustain the former marshland. Some marshlands were burned and buried pipes underground helped to carry away water for quicker drying.
The drying of the marshes lead to the disappearance of the salt-tolerant vegetation, the plankton rich waters that fertilized surrounding soils, 52 native fish species, the wild boar, Red Fox, buffalo and water birds of the marsh habitat.