I say we wait for them to settle, and since we have open borders, no matter what, have an axe sit on the iron. Then prepare for war. If we can get the iron in our borders, than yay for us, but if we can't, the moment a worker aproaches the iron, we kill him with the axe. Also, do we have other sources of iron, because if we do, we should pump out swordsmen for the now inevitbale mongol war.