Discrimination against African Americans was bad. But it was even worse against Native Americans. The 14th Amendment declared African Americans citizens. But it did not do that for Native Americans.
Settlers wanted free land for their cattle to feed. As they took land, they left less and less for bison to graze. Bison are also known as American buffalo. Natives had long relied on bison for food, clothing, and tools. An estimated 30 to 60 million bison once roamed the prairies. Around 1830, settlers and businesspeople started killing huge numbers of them. By 1884, fewer than 1,000 bison were left in the U.S.
The land and food Native Americans relied on were disappearing. Natives were forced to sign treaties with the United States. These treaties made them move to reservations. Those are areas the government set aside for them. Gold was found in the Black Hills in the 1870s. So U.S. soldiers forced the Sioux Nation members living there to move to reservations.