I mean, I don't think they add much to the gameplay in this case. In EU4, the game the map is based on, they weren't fun to play or fight against, they were so inaccurate and a pain to deal with that I always disabled them. Anyway, the game is easily modifiable, so if in the future I or someone else wants to make a map of the tribes from North America or Australia, it would be easy to do. The map itself isn't the important part here, the idea is to provide a framework where any kind of scenario can be played.