Some time in the past, there is an island of disparate peoples happily carrying on with their lives. Each group has its own rules, traditions and customs. Life is hard, but there is order and implicit ownership of lands that they have lived on for generations.
Then soldiers from a foreign nation that they’ve never heard of arrive. They kill many of the natives, rape some and enslave others. Agreements are made that the natives don’t really understand, and as time passes they become second-class people in a place that is no longer theirs.