A neat sim, based on the Schelling Segregation Model and implemented using the Anylogic simulation tool in agent-based mode, shows what happens when you have two divided communities living in the same place such as a city or a country.
The shared living space is modelled as a very large chessboard and each house owner has a preference for living next to their own kind (race, tribe, religion, class, sexual preference etc). If this preference is met then they stay where they are otherwise they move house which leads to self-organisation of the chessboard. The simulation shows that even a mild preference for living next door to your own kind soon produces a totally segregated society. Also when you play the demo try putting a very strong preference (greater than 80%) on living next door to your own kind. This produces total chaos .... due to the fact that everybody just keeps on moving house and no stable state is ever reached!
This is what I call a "Eureka Simulation" as it gives the players a blinding flash of insight, in this case, even a very slight level of social intolerance brings devastating consequences in the longer-term !!!