Who was the last Indian tribe to sign a peace treaty with the US?

The last Indian tribe to sign a peace treaty with the United States was the Sioux Nation, specifically the Oglala Lakota, in 1868. This treaty, known as the Treaty of Fort Laramie, established the Great Sioux Reservation and guaranteed the Lakota rights to their lands. However, subsequent violations and conflicts undermined the treaty, leading to ongoing disputes.