Before the state of Montana was named, and before it even became a state, the Native American people lived there on their own. Whether they knew that there were other people out there and whether they thought that those people might come to take their land is only speculation. They were just interested in raising their families, and they hunted, fished, and grew crops there, just like in other states. Even though there were quite a few different groups of Native Americans, there was plenty of land so they could put space between them if they didn’t get along.
Most of the tribes were able to co-exist because they had enough space, but that didn’t mean that they always got along. There were different tribes even different areas, like the Crow, the Blackfeet, and the Cheyenne. Some of the tribes were small and kept to themselves, while other tribes were very large and exerted a lot of influence. The smaller tribes mostly just tried to remain apart from the larger ones so as not to antagonize them.