I've recently been fixated on the rise and fall of the Mongol Empire. Aside from the 50 million plus deaths that occurred as a direct result of the Mongol conquests, what we're it's pros and cons?
a quick answer:
fear of the mongols and other factors lead to less bandits/highwaymen and therefore safer and easier travel for merchants and others.
pros - more accessible and easier trading, better flow of goods, ideas, etc.
Con - also better flow of diseases the black death is the major culprit