He lived in a brutal era as his own youth demonstrates. He was, indeed, benevolent by the standards of his time, and he and his decedents did a lot to open up trade routes from east to west...and kept them safe for travel which was a situation never experienced up until then. Unfortunately it was these trade routes that allowed the black plague to find it’s way to Europe. I think it was more Kublai that had the dealings with the Chinese.
It is my undertanding the the Black Death came into Europe from Middle East Ports by ship rats debarking in places like Italy. The rats might have gotten to the ports via the trade routes, but the final step was by sea. An interesting book is Rats, Lice and History by Zinzer (sp?).