cuchulain said:
how do u stop them attacking? i know it's probably obvious but...
You can't stop them attacking. The best strategy in my opinion is to try to outsiege them, so to quicker conquer provinces back then they can conquer provinces.
That means you will have to use several armies, some to fight the mongols head on to prevent them from sieging and some to go behind the back of the mongol armies and siege and conquer there provinces. If they don't have any provinces of their own the armies are gone.
This is not easy of course, you can't do it to early because then their armies are still to close together and can support each other and you can't start to late because then they are to powerfull.
I myself have just edited the size of the Mongol armies in the
crusader kings/db/events/Mongol_invasion_events.txt file. Their armies are now much smaller and they don't really bother me.
I just don't like the Mongol invasions cause it will lead to unhistorical unrealistic conquest in the game.