After a series of bloody battles congress passed new Indian policy in 1867 relying on Indian "concentration" forcing natives to live in small concentrated areas a fration of the size they used to reside in.
The white's relentless slaughtering of the buffalo also contributed greatly to the downfall of the natives.
Famous riflemen such as Buffalo Bill were hired by railroad companies to thin herds.
Many Indians did resist the U.S.' demand to leave their lands. This more often than not ended in bloody battles. Although some did put up great resistance like the one General Custer faced the Anglo Saxon Americans prevailed as the dominant fighters forcing them back.
In Colorado during the winter or 1864 the Sand Creek Massacre occurred where 105 women and children were killed. In California "Indian Hunting" became sort of sports where civilians would take to murdering 5000 INdians within 30 years for rewards.
A revive in old cultural ways saw the rise of the "Ghost Dance" ritual where tribe members would dance to scare the Americans away and bring the buffalo back.
At the Battle of Little Bighorn in southern Montana in 1876 tribes surrounded General Custard and his 264 men and killed every single last one for the biggest tribal victory of that time.
On December 29th, 1890, the Seventh Calvary, once Custard's had rounded up 350 captured Indians. A conflict arose killing 50 US soldiers but the army quickly fought back to an almost defenseless incredibly weak effort. The result was a strait massacre.
Congress passed the Dawes Severalty Act of 1887 which was aimed at destroying all of the natives official ownership of land and to grant smaller portions of land to individual families. Had an ideology of assimilation