Im playing on VH/VH for Russians.

I was waitnig for Mongols, because on my west boarders Im kicking shit out of Danish ans Venetian. Poles and Hungarian I already destroyed.
There is one good tactic: - dont take all cities u conquer, just rob them, take only strategik city in the begining. After u will get all them. So ,y Russia now has lots of cities huge armies, mostly on east borders and best economy in the known world (except Mongol of course).

Back to mongols. When i got a messege about Mongols caming, I made 2 high end armies on my east borders, and made my great King (7 stars) with his not big, but expirienced army (all units with at least 2 silver, some with gold) go to east borders.

i had only 1 battle with Mongols until today. One my expensive, but newbie army faced 3000 Mongols (I had only 1000 soldiers). So they defeat me, but I killed around 2000 of their forces. I managed to defeat 1 and second wave, 3 killed me.
Now I have 3 Armies assunlting Kiev. In Kiev I have full garnizon of high end soldiers (lots of good archers), but poor general. Its really fun. Im going to play Kiev deffence today. Moreover as soon as my King (he is near Kiev) will get some reinforcments, he will attack. Im sure even if they would took Kiev, they will lost a lot of force, my king with his victorious army will tear rest of them apart.
I like Mongols their making game chalenging.