Crusader Kings II

[Sarmatian]

I like playing in the eastern part of the map and so far, even though I've been generally successful, the Mongols come and kick my behind every time.

Now I've tried playing as Cumans (there's an orthodox christian cuman duke in 1066), thinking maybe I can beat them with their own weapon - horse archer retinue but it's cca 1130 now and I have a very small retinue and I don't think I'll be able to rival them in numbers, not even close.

Which, in your experience is the best troop type to combat the mongols? I've seen some advocate either heavy infantry or pikemen?