Answer:
Gold.
Explanation:
A series of clashes between the Northern Cheyenne, Lakota Sioux and the United States that took place in the years between 1876 and 1877 for the occupation of the Black Hills was known as the Great Sioux War. The discovery of the gold in the Black Hills and the U.S government's desire to establish its control over the Black Hills were the main causes of the war.
