Red Cloud's War was a conflict between the United States and several Native American tribes, primarily the Lakota Sioux, from 1866 to 1868. The war arose from tensions over the U.S. expansion into the Powder River Country and the construction of Bozeman Trail, which disrupted the tribes' hunting grounds and way of life. The war is named after Red Cloud, a prominent Lakota leader who successfully led his people against U.S. forces. The conflict ended with the signing of the Fort Laramie Treaty in 1868, which recognized Native American land rights and established the Great Sioux Reservation.