How the mighty have fallen. Once one of the largest empires in history. Now, I think there's more horses than mongolians themselves in Mongolia.
Problem is, it was over pretty much a vast wasteland, and the empire wasn't that high tech, nor a bastion of learning...slash and burn personafied.
Imagine khan's army versus the greats of history's Empires, it would get crushed. Man, the horses alone were short, slow and couldn't carry that much. Like having a Honda Civic burdened down with 5 4 obese people, going up hill.