What causes a reemergence anyway? I mean I know that it's a long lost heir or whatever and I know the rules for where a reemergence occurs, but is there any way I can keep a reemergence from occuring when it comes to a faction I've eliminated?

For example, I just eliminated the Turks in a Byz campaign I just started. I didn't mean to kill their king; I meant to let him escape and kill almost everyone else and just let him rot in one little nothing province the rest of the game. But I got lucky and some Triez archers took him down. I have now moved on to the Egyptians and plan on moving all the way across N. Africa but would rather not have to deal with the Turks popping back up in my back yard
Does the loyalty rating in their old provinces have anything to do with it?

Thanks,

Micah