Suppose Ogadai doesn't die so shortly after the battle of Liegnietz and lives another 15 years. And instead of spreading their empire in every direction they decide to concentrate solely on Europe. How far could they have gone with their superior arms, tactics, cavalry, and resolve? Do they conquer all of Europe? Could even a combined army of all the major nations quell their advance? What would be the consequences of the Mongols razing all the great ancient cities to the ground like Paris, Rome, Naples, Brussels, Rottemdam, ect?