I read in a post the question DO factions re-emerge if they are exterminated? well no...but in the kingdoms addon this re-emerging stuff has been at least thinkered with!!! because if you capture a city form the turks in crusades and let it go rebel it won't turn grey/rebel(slave) but to the original faction that had build it up...so my thoughts for the future is that Empire Total War will bring it up again in a form or another.....