South Dakota historian Doane Robinson is credited with conceiving the idea of carving the likenesses of noted figures into the mountains of the Black Hills of South Dakota in order to promote tourism in the region. His initial idea was to sculpt the Needles; however, Gutzon Borglum rejected the Needles because of the poor quality of the granite and strong opposition from the Lakota (Sioux), who consider the Black Hills to be sacred ground; it was originally included in the Great Sioux Reservation. The United States broke up the territory after gold was discovered in the Black Hills. The mountain into which it was carved is known to the Lakota Sioux as Six Grandfathers.