Most of us probably know how their genocidal conquest of Khwarezm was largely a result of the Persians' appaling treatment of Mongol emissaries, and how without such an atrocity the region, if attacked at all, would probably have been spared the excessive brutalities of OTL's campaign.
I'm asking you guys for similar ideas. Bring up things which could've went happened in a different way, resulting in more peaceful takeover of entire regions. The Mongols having easier time cracking certain nuts may have made them less pissed at their enemies, and may have held them back from committing worse atrocities. Or, some foes just not outright provoking them, like Khwarezm.
This idea fascinates me because as opposed to perhaps most empires, the Mongols, in a seemingly paradoxical way, did contribute a net positive economically, as the extensive Eurasian trade network created by them made up for the losses their destruction brought upon their foes. As far as I know, at least. So the idea is to see that gap widen to the greatest possible degree.