The Mongols undoubtedly wiped out entire ethnic groups during their conquests. They killed millions of people. In some cases languages would have been wiped out. You just don't hear much about them these days because dithering over the genocide of peoples we know little about back in 13th-14th century is not in the zeitgeist the way modern colonialism is.
It's not surprising, and in fact quite obvious, that any historical event has "good" impacts as well as "bad" ones. But to speak of the Mongols as "preservers of knowledge and culture" is silly. I suppose they could have done more to wipe such things out, and didn't, but it hardly seems like something they deserve credit for. Certainly you could make the argument the colonization of the Americas really did not in any way resemble Mongol extermination campaigns.
https://en.wikipedia.org/wiki/Destruction_under_the_Mongol_E...
It's not surprising, and in fact quite obvious, that any historical event has "good" impacts as well as "bad" ones. But to speak of the Mongols as "preservers of knowledge and culture" is silly. I suppose they could have done more to wipe such things out, and didn't, but it hardly seems like something they deserve credit for. Certainly you could make the argument the colonization of the Americas really did not in any way resemble Mongol extermination campaigns.