I think the Mongols caused more cultural destruction. The reason for how they did a lot of bad things is that they killed a lot of people. They also sold a lot of stuff to other places, so they weren't all bad.
One of the bad ways they killed people is a Mongol soldier killed their prisoners by shooting them with a bow or burying them upside down. In 1237 there was a war and Kozelsk was in it and there were no survivors at all. The Mongols would use catapults to help them in war. They were so brutal, if some soldiers ran away, their fellow soldiers would kill them. They would also conquer