If your're interested in the history of the Mongol invasions, I'd highly recommend looking into the podcast Hardcore History by Dan Carlin. He did a five part special, totaling over twelve hours in length, discussing the Mongol conquests. I listened to his analysis as a counterpoint to Jack Weatherford's "Ghengis Khan and the Making of the Modern World", and found him to be outstandingly informative.

He provides excellent context to any discussion of the more direct impacts. I'll leave you with but one small tidbit of his description of their invasion's impact, though: according to some historians, the area now known as Iraq only recovered the standard of living it had enjoyed prior to the Mongol invasion in the hundred years. In short, the impact was absolutely devastating.

EDIT: Hardcore History