The Sioux Indians' best achievement was The Battle of Little Bighorn, where the Sioux Indians at an Indian camp fought off early American forces when they tried to take their territory. The Indians killed many Americans, including general George Custer, a major U.S. military leader.
Sitting Bull and Crazy Horse. Sitting Bull was elderly and did not fight in the battle, but he was widely respected among the Sioux, and his vision of a Sioux victory was instrumental in rallying them to fight.
Well to start with, there is the fact that Sioux means "Little Snakes" and the fact that they were very widespread around the continent of North America. Also, the Sioux tribe teamed up with the Cheyenne tribe to defeat George A. Custer in the battle of the Little Big Horn.