How to use this in fantasy? Well, I'm a bit of a nut for linguistic topics, but linguistics often underlies a population's sense of identity. The notion of people being forced to leave, or voluntarily leaving their homes due to a sense of nationalism, patriotism, and identity with one rather than another state, the notion of seething irredentism or revanchism leading to riots, exodus, or other political games--this would be something that any fantasy RPG should be glad to incorporate. The notion that all inhabitants of all places just sit quietly, happy with their situation all the time, is not one that history itself suggests is likely. Plus, that kind of intrigue is much more exciting (to me, at least) then finding a hole in the ground with monsters in it.