Complex sentence: Native American anger at settler intrusion into the hunting grounds lead to Red Cloud's War and the Treaty of Fort Laramie in 1868, by which the US granted the territory of the Black Hills and the Powder River Country to the Lakota people.
Split into simpler sentences: Native American anger at settler intrusion into the hunting grounds lead to Red Cloud's War. They settled the conflict with the Treaty of Fort Laramie in 1868, by which the US granted the territory of the Black Hills and the Powder River Country to the Lakota people.