For me, the most surprising thing that I learned was that Europe was actually having significant hardship before the Black Plague actually occurred. Their economy was suffering from the continuous expansion and the arrival of the Mongols and the Ottomans had disrupted trade routes, and certain areas of Europe were edging into depression. Additionally, the climate had changed significantly to a cool and wet climate that resulted in lower crop yields. The Church was doing poor also. These difficulties only aided the destruction when the Black Plague did hit and essentially just worsened what was already bad.
