> They require a homogenous society to function? To what do you attribute it? Most definitely a homogeneous society. Without something to bind the people together there's no chance a city (or a country) will survive. On top of that, the larger the city is the more important. Outsiders in a small town can be ostracized if they don't fit in. In cities they clump together and create mini-societies within the larger one. I can remember when Dearborn, MI didn't have any islamists. Now they're running their section of the city and will soon take the whole thing over.