I agree that they are names of tribes and not people, and are therefore not legitimate in my opinion either. They can also be seen as offensive, not just illegitimate. I think for the sake of keeping this conversation civil you may just want to pop over to one of the many conversations (or feuds as some may think) on the name.
Here is one:
http://www.behindthename.com/bb/arcview.php?id=782408&board=baby
Enjoy!