Group of mountains in western South Dakota and northeastern Wyoming, U.S. Occupying about 6,000 sq mi (15,540 sq km), they lie between the Cheyenne and Belle Fourche rivers and rise to a maximum elevation of 7,242 ft (2,207 m) at Harney Peak. Their name refers to the dark appearance that their rounded hilltops and well-forested slopes present at a distance. The Sioux Indians were guaranteed treaty rights to the region in 1868; however, the discovery of gold in 1874 led to an influx of white miners and to the Black Hills War (1876), including the Battle of the Little Bighorn. Tourist attractions include the mining town of Deadwood, Mount Rushmore and Jewel Cave national monuments, Wind Cave National Park, and Custer State Park, all in South Dakota, and Devils Tower National Monument in Wyoming.