I just listened to Dan Carlin's Wrath of Khans and he references many times about the ultimate benefits of Genghis Khan, but without much detail and only in order to ask whether the benefits were worth the cost in life.
I'd like to get the "other side", so to speak, and wondered what were the benefits? He mentions trade routes and temporary drop in crime, but do we have any way to quantify that or put that in context? Any long-term benefits? What happened after the Khan empire fractured?
Well by the end of it a pretty extensive trade network was made larger and safer with the Yassa. As well religions that were relatively isolated could freely cross from the western world to the eastern one.
I would say the most controversial one is one that is pretty difficult to truly pin down. You remember when he was talking about Prester John and the crusades? So the christian European crusaders had the theory that there was another christian kingdom that was coming in from the east like a vice to crush the Islamic forces in the middle east.
Obviously they were wrong about him being a Christian king, but they weren't wrong that Ghengis was crushing them from the east. It's damn impossible to quantify, because its one of those questions that can be asked a thousand times but no real answer could be given.
What would our modern world be like if the Kahns didn't divide the Islamic forces? At that time the Islamic world was very powerful. They had some of the best technology and advanced philosophy and sciences. As well they had massive armies and wealth beyond measure. I would really like a military historian to weigh in here about the might and capabilities of early 12th century Islamic world, but I do not think it would have been outside the realm of possibility for them to push into what we modernly think of as Europe.
As well think of the history of the western modern world that we have. The western world was the only one untouched by the Mongol horde (vodka be praised). The entire world surrounding Europe was just trampled into the dirt by the mongols. Within 300 years the world started to be carved up by the new emerging global power based in the western European world. And that hasn't really stopped.
It's impossible to quantify, but the Mongols went into the forest and cleared out the canopy allowing the small European trees to grow massive and then dominate the forest.
It's not a benefit or a detriment, which implies some relative moral justness or right. The mongols simply affected the world in incalculable ways that birthed the world we live in today.
...I really wish they didn't destroy the library of Baghdad though. That's that I think about if I had a time machine. Going back and taking pictures of all the documents before they were lost forever.
you may be interested in some previous discussions
The Mongols are typically portrayed as excessively violent and cruel. Is this true, or were they just as violent as every other country at the time? includes the question Also, did anything positive come out of the mongol empire?
Are the Mongol Khans ever cast in a positive light in China or Russia?
What benefits/improvements did Khubilai Khan bring to China during the Yuan Dynasty?
Was the Mongol invasion of early medieval Russia good or bad for the early Russians?