Born about 1868 or 1869, Amos was the son of Bad Heart Bull (Tȟatȟáŋka Čhaŋtéšiča) and his wife Red Blanket (Tȟašína Lúta Wiŋ).
At the end of the Great Sioux War of 1876-77, the Bad Heart Bull family surrendered at the Red Cloud Agency on April 18, 1877, several weeks before Crazy Horse.