Answer:
Guns
Explanation:
Gunpowder was invented in China during the Tang Dynasty, and it reached Europe in the 13th century. In the following decades, gunpowder weapons spread, while traditional steel and iron weapons such as swords decline.
This led to the development of professional armies that used guns instead of swords. The nobility armies declined, and as the nobles could not claim to be protectors of their manors, feudalism declined as well.
