What were the social, political and economic factors behind anti-black violence?

How did the discovery of gold impact american indian territory in the 1870s? a. war broke out among american indian groups when warring chiefs signed new treaties with the government. b. war broke out when white settlers pressured the government to take the land from american indians. c. war broke out when white settlers pressured the government to let american indians keep their land. d. war broke out when white settlers tried to buy land from warring american indian groups.