The Murray Darling Depression , also known as the Murray-Darling woodlands and mallee, is a 19,717,651 HA biogeographic region and an ecoregion in southeastern Australia consisting of a wooded plain through which flow two of Australia's biggest rivers, the Murray and the Darling. There are several modern human settlements in the bioregion including Ivanhoe and Manilla, but the region also contains some of the oldest known human occupation sites in Australia.

The Darling River is the third-longest river in Australia, measuring 1,472 kilometres (915 mi) from its source in northern New South Wales to its confluence with the Murray River at Wentworth. Including its longest contiguous tributaries it is 2,844 km (1,767 mi) long, making it the longest river system in Australia. The Darling River is the outback's most famous waterway.