The draining of the Mesopotamian Marshes occurred in Iraq and to a smaller degree in Iran between the 1950s and 1990s to clear large areas of the marshes in the Tigris-Euphrates river system. Formerly covering an area of around 20,000 km² (7,700 sq mi), the main sub-marshes, the Hawizeh, Central, and Hammar Marshes and all three were drained at different times for different reasons.