How did the fall of the Roman Empire led to the feudalism In the Middle Ages

The Roman Empire provided safety and protection from outside forces due to their vast army. When the Western Empire fell, Vandals, Visigoths, and other germanic peoples started to settle the area. Many germanic kingdoms began to sprout up. Without an army to protect the poor, people began turning towards Lords (and those who had the means for an army). They entered into an agreement where peasants would work and maintain their land in exchange for protection from invaders. It was a mutual agreement. Eventually, this turned into the Middle Ages as we know it.