With the memory of Milslovic's genocides fresh on a lot of people's minds and Muslim terrorism being all over the news, I don't think a movie featuring a battle between the Serbs and the Muslims would go over too well right now. It would set about like if "Enemy at the Gates" had been released in the States during the Cuban Missile Crisis.
Seriously, if you're worried about overused stereotypes, Tennessee as an example of potentially violent backwater places is probably overused too. Everybody remember "Deliverance"?
Fact is, it would be hard to find too many regional characteristics of any area that have not been over-used in entertainment by someone. Plus, it's easy to go with the places you know the most about. Most of the historical M&B mods are falling into this pattern as well - ONR doing Japan, HW the Crusades, and Mesoamerica the Aztecs, because those are the best-known examples of each of their areas. There are not major mods based around fighting in India, Malaysia, or Argentina, because everybody's reaction would be "Where?" For that mater, and relevant to TLD, Tolkien used the most common perceptions of ancient warfare as well ... European weapons and equipment of about the time of the Crusades.
When we get custom skeletons working in the next M&B version, it might be fun to try to break this pattern and do something less well-known ... say, Medo-Persian Empire, featuring chariots and war elephants. Something that would break from the common patterns, behaviors, and equipment profiles and get people into a very different mindset - equally diverse, but logically different.
Until then ... well, I guess we live with the stereotypes. If you can't fight them, join them.