The Mesopotamian Marshes were drained 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. The marshes formerly covered an area of around 20,000 km2 (7,700 sq mi). The main sub-marshes, the Hawizeh, Central, and Hammar marshes, were drained at different times for different reasons.