e.g. In Northern Ireland (and parts of Scotland) there were clashes between Protestants and Catholics. I used to see them all the time on the news when I was a kid. There are two distinct groups (both Christian) that have not co-existed very well historically. I don't know if you would call them different cultures but they are distinct enough to cause a schism.
If you have immigration into one country. These people with different cultures, have different values. That creates a schism between them and the natives.
e.g. You can see this in Spain between British Expats and Spanish Nationals. The British Expats essentially live in particular areas and they are their own subculture in Spain (I know I was one). I lived the entire time in Spain learning nothing more than being able to order Beer, Lunch, Taxi and working out how to use the automated bill payment machine at the BBVA.