I was going to add in the title "and is owned by the primary nation for it's culture" but that wouldnt fit. So as the title says, if i take a province, and nobody but me has a core there, and I am already the primary nation for that province's culture, it has been my experience that sometimes you get rebels for tags that dont have cores at the start, like banten for example, but not in all cases. What is it that determines what tag the separatists side with in such an instance? The reason I ask is that I sometimes like to try to play obscure or rare tags, and this could be useful to know to put some of them on the map.