The Black Hills War was a period of conflict lasting from 1876-1877 which took place in a region of the United States now covered by Montana and North Dakota. This series of skirmishes and battles became famous due to the involvement of General Custer, who fought in the Battle of Little Bighorn in 1876, dying along with almost half of the cavalry he led into battle. Ultimately, the Black Hills War was resolved with a treaty, but not without significant bloodshed in the process.
Native Americans have lived in the Black Hills area for thousands of years, with various tribes controlling these famous mountains at different points in history. By the 1800s, the Lakota Sioux had gained control of the Black Hills, and they had established a treaty with the United States which allowed them exclusive use of the land. However, in 1874, an expedition led by none other than George Armstrong Custer found gold in the area, triggering a gold rush.
The Lakota Sioux became extremely angry as intruders entered their sacred lands to search for gold, and they started fighting back, citing the treaty, which explicitly forbade non-Indians on the land. However, the United States was more interested in the gold than the treaty, and once the Lakota attacked American troops directly, the Black Hills War was launched. In a series of sometimes very brutal conflicts, American soldiers vied with the Lakota and their allies to control the Black Hills.
Ultimately, the two sides established a treaty to put an end to the Black Hills War. In the treaty, the Lokota ceded part of their sacred land, in return for an expansion of their reservation in another direction. The gold rush petered out shortly afterwards, but thriving cities like Deadwood and Custer City had been legitimized, thanks to the treaty, and they continued to grow.
The events of the Black Hills War were repeated in many other parts of the United States with different Indian tribes as the American government tried to seize control of as many valuable natural resources as it could. The reservation system may have originally established with the lofty goal of providing Indians with specific territory, but it ended up being used as a tool to corral Native Americans. Many tribes were forced into unfamiliar territory, and ceded land of poor quality which no one else wanted, creating festering resentments which still cause social problems in some parts of the United States.