Originally Posted by GrandInquisitor
The player will lose a city/cities to the Mongols. If they breach your walls, you die. Spears are completely rundown by their cavalry. The only assault I've beaten was at Antioch as the Turks (with those insane catapult towers), when my full garrison of spears and Halberdiers killed the general. They had another army, but it never tried to round the city to the breach, so I was spared. I'm not sure about anyone else, but my most heavily fortified territories weren't a match.
And to answer another question, don't give them anything -- territories or an alliance. In my experience, they don't care about gifts. They'll attack you -- the player -- full-force regardless. Make them bleed for their conquests as much as you can (and it might not be much).