Things to keep in mind while researching Native Tribes of Missouri:

The native tribes of Missouri did not all live in Missouri at the same time. Also, I've noticed that some of the websites say different things about native tribes in Missouri. It is hard to say what actually happened from these sources since Missouri at the time when settlers were moving in was a time when recording information about native tribes was not a priority. Claiming land for settlement and farming was the priority for settlers and the government. Native people were seen as a threat by many settlers and the government. Our best source of information comes from primary sources created at the time of encounters between explorers, settlers, and the military of the United States government. Keep in mind that these primary sources have a slanted view of Native people because of how the groups saw native people. In modern times, researchers try to provide a more balanced view that has been informed by native people and historical evidence. Since there aren't any official tribal homelands in MO anymore, it can be difficult to find information. 

Links

1. Seven Tribes of Missouri
2. State Historical Society of Missouri
3. Missouri Life Article: Part 1 Tribes of Missouri: When the Osage and Missouria Reigned
4. Missouri Life article: Part 2 Tribes of Missouri: Things Fall Apart
5. Missouri Life article: Part 3 Tribes of Missouri: Homecoming
6. The Illini from the State of Illinois Museum