The perspective most likely to be held by a European living in a country conquered by the Mongols would be:
The Mongols were responsible for the murder of millions of people in their conquest of European countries.
This perspective reflects the immediate and personal impact of the Mongol invasions, which often involved significant violence and destruction. While there may have been other viewpoints about the Mongols' role in trade and knowledge transfer, the traumatic experiences of conquest would likely dominate the perception of someone from a conquered region.