How and why did federal policy toward indian peoples change in the decades following the civil war

So many things encouraged a good number of white settlers to migrate into new states and territories, this lead to serious competition for space and resources. One of those discovered resources was gold, this lead to the identity of the Nez Perces tribe to be challenged. It also made the Federal officer to end rules that encouraged tribalism and allowed Indians into the American conventional space. Some tribes were preserved because they experience geographical isolation, but the plan to have a permanent territory for indians did not materialize. The Indian war ended due to too much of skirmishes.