There Goes the Neighborhood

When two conflicting cultures end up sharing the same space, one instinct is to convert to one side's belief.  This is what the Europeans did when conquering the Americas, and it didn't work so well, considering that both sides wanted to keep their old ways of life.  Another instinct is (sometimes initially, or in this case after conversion attempts) to consider people who don't share your way of life hostile and filthy and declare war on them.  One example of this is the Rwandan Genocide in which the Hutus took to extreme measures (given they're an extremist group) and wiped out the whole Tutsi population with machetes- about a million.  In other cases, however, the cultures may decide to blend together and keep certain aspects and rules from each of their set of beliefs.  This would trigger intense societal changes depending on how different the groups were.  Actually, in our own city there are big examples of this.  Being a very diverse city, Chicago has many neighborhoods where different people moved to, and their culture along with them.  Because of this, in Chicago, for example, anyone can just take a step out of an Indian neighborhood and walk into a Jewish neighborhood, or maybe be standing in both overlapping at the same time.  When the Europeans took over the Americas, they regarded the Native Americans as different and unwanted, so they were taken over.  When the English sent people over to the East coast of what is now the U.S., they turned into colonies.  In this case, what was one nation divided into two: the revolutionaries and the nobility.  Notice that the Native Americans weren't colonized- they were just eschewed.  Later in U.S. history, the Americans didn't like the idea of other civilizations (aka. "Indian scum") existing within their country, which lead to the Trail of Tears.  Many hostilities can arise when there are different cultures occupying the same space, but it is up to the people to avoid them.