The Palouse encompasses parts of southeastern Washington, north central Idaho and, in some definitions, parts of northeast Oregon. It’s a major agricultural area, primarily producing wheat and legumes. Sometimes the term is used to refer to the entire wheat-growing region, including the Walla Walla County, the Camas Prairie of Idaho, the Big Bend region of the central Columbia River Plateau, and other smaller agricultural districts such as Asotin County, Washington, and Umatilla County, Oregon. This larger definition is used by organizations such as the World Wide Fund for Nature, who define the Palouse Grasslands ecoregion broadly. The peculiar and picturesque loess hills which characterize the Palouse Prairie are underlain by wind-blown sediments of the Palouse Loess that covers the surface of over 50,000 km2 (19,000 sq mi) on the Columbia Plateau in southeastern Washington, western Idaho, and northeastern Oregon.