How did the fall of the Roman Empire contribute to the developmant of feudalism in Europe?

when the roman empire fell it created small farms with land owners and workers (the workers come so that they dont have to pay taxes because of the deals that wealthy land owners made with the emperor to only pay a certain amount then never have to pay again) and when they did this they were left vulnerable to the Normans or better known as vikings that came down and started to burn down farms and kill all its inhabitants so the feudal system is what they came up with to protect them selves as they became very spread out and had very little resources

so in essence it was created for the protection of the used to be romans so that they may have enough protection and resources to survive