If u like to play defensive with some  villagers to repair and castles
u can do it. Develop 2 or more castles of Mongol civilization and 
garrison elite mangudai inside castles for 20 units each castle. After
doing it,you can see the gr8 results. Even with other civilisations you
can put archers inside castles to improve ur defence,it also heals ur 
units wich are inside castle.