“Thus the white men and Native Americans were able, through the spirit of goodwill and compromise, to reach the first in what would become a long series of mutually beneficial, breached agreements that enabled the two cultures to coexist peacefully for stretches of twenty and sometimes even thirty days, after which it was usually necessary to negotiate new agreements that would be even more mutual and beneficial, until eventually the Native Americans were able to perceive the vast mutual benefits of living in rock-strewn sectors of South Dakota.”