[crunchyfrog]

All tribes were being pushed westward by white settlers and it inevitably led to conflict among the tribes. But Lakota definitely did not "genocide" the Cheyenne as is obvious by the fact that they still exist in Montana and Oklahoma.

And regardless, this has nothing to do with the US government signing a treaty giving the Black Hills to Lakota "forever" and then just a few years later driving them off the land. The US government itself says what it did was illegal by its own laws.