I would think a high fantasy with low fantasy elements would be interesting. By High Fantasy I mean using African Mythical races instead of European if you are going for African like tribes or Native American Mythical races if you are going for Native American tribes, but it would still have low fantasy elements like Witch Doctors.
Edit: Here is an idea, you could allow Native American and African like tribes to exist at the same time in the same area, so we can have a more diverse world culture and race wise.