What was the main problem the government had with the native americans such as the sioux?

The Sioux didn't want to give up their land, but the US wanted to make houses and live there. They had to use interpreters because most didn't speak each other's languages. The Sioux signed treaties, either willing, or forced to. Some treaties were unfair and favored the US. (This is a bit favoring the Native Americans, I will admit)