All of the following were long term impacts of the Mongols EXCEPT: O Mongol fighting techniques led to the end of knights' use of armor in Western Europe
The development of medical vaccines to protect from the Black Plague that the Mongols helped
spread
O Mongol's ruled successfully due to their understanding of centralized power and their use of
international law and this would be copied by Europe, Asia, and Southeast Asia
The era of walled cities came to an end due to the siege techniques used by the Mongols

Option: The development of medical vaccines to protect from the Black Plague that the Mongols helped spread.

Explanation:

The Mongols are the Nomadic people from the eastern steppe lands of Asia that formed an empire under Genghis Khan. Mongol Empire used biological warfare technique to kill people in the Crimean peninsula. The Mongol army attacked the Crimean city of Caffa, led people to flee and expand the plague from Caffa to the Mediterranean.

There were no medical vaccines to protect from the Black Plague as the Mongols spread it in the Crimean peninsula. The plague killed millions of people in Europe.

ok so u have2 basically