But.. but.. Europe has got shining knights and God, and hellhamster. Do not forget its last asset.Man, the European chauvinism is unbearable in this thread. There's a reason that, as a person descended from European culture, I know the name Ghengis Khan 800 years later - because Europeans 750 years ago were so scared of him it still echoes to today. But, sure, your European trickery would have carried the day.
I mean rivers, right? No one else ever built cities on them. And trees - that's going to really mess them up.
In the real world, the Mongols obliterated the Chinese, who were larger, more unified, and more technologically advanced than Europe. They crushed the middle east, which was again larger, more unified, and more technologically advanced. They took down cities that were larger and better fortified than any in Europe. They smashed Russia, across trees, mountains and rivers. The Mongol army was better organized and more mobile than anything in Europe. It had better siege capabilities (thanks Chinese engineers), better communications, and better supply corps than any European army of the era.