What's Going on With the Mongols?

The Mongols are by far the most dangerous invaders of this part of the world, like in all of Byzantine and Roman history so far. They seem to have a very advanced capacity both for learning and for picking up new techniques. If they encounter a group of people who they like and think would fit well within their own society, they will often insist on that society being merged with the Mongols. The background of this is the historic tensions and relationships and alliances between the Central Asian Step region and the nomadic tribes therein.