Along with the conflicts with the whites, Indian hunting, the act of hunting and killing Indians, began to grow in popularity, especially in California. Rewards were often offered, and many whites did this with the goal of the literal extermination of the Indians.
Despite having their own reservation, Indians in the territory were not completely safe, as whites were creeping into their territory once more. This caused the Sioux to rise up and fight, their leaders being Crazy Horse and Sitting Bull.
The Battle of Little Bighorn in Montana of 1876 is one of the most famous. Tribal warriors managed to surround Colonel George A. Custer and his troops, as the chiefs had gathered 2.5k warriors. However, due to the lack of resources to supply themselves, the power of the Sioux eventually collapsed.
With the Indians' lives being ripped from them right before their eyes, the Indians grew desperate, and they turned to the prophet Wovoka, who spurred a religious revival from Nevada to the plains.
Of the many religious practises, ghost dances became especially prominent. They created visions of the return of the buffalo and the eventual disappearance of the whites. The reservation agents were intimidated by these dances, as they feared the dance would incur hostilities.
This resulted in the Seventh Cavalry being sent to attempt to round up 350 Sioux Indians at Wounded Knee on December 18, 1890. However, fighting and resistance broke out, which resulted in the death of 40 white soldiers and 300 Indians.