Feudalism and manorialism developed as a direct result of the 9th and 10th century invasions. During the 9th and 10th centuries, the Kings of France, Germany and other countries in that region were unable to cope with invasions from the Vikings of the north, and from the Magyars and Muslims of the east.
The Kings were not able to offer protection to their subjects from these ruthless raids, so the subjects had to turn to local noblemen for protection. These subjects entered into a sort of contract with the Lord of their particular region. They became known as Serfs, and would work on the Lord’s land for two to three days per week, in exchange for protection against the Viking raids. The Serfs would use the other days to work on their own plot of land (which ultimately belonged to the Lord), and were able to use the goods they produced to consume or trade. The Lords exercised political authority over their realms, collecting taxes, maintaining the infrastructure, etc.This system was known as manorialism.
In order for a Lord to provide this protection, he would appoint warriors, called Vassals. These Vassals were given a portion of the Lord’s land, called fiefs, so they could support themselves, and have enough time to practice their combat skills. This relationship is called feudalism. The Vassals did not only protect the Lord and his Serfs, but also offered advice to the Lord. This was the basis of modern Parliaments. The Vassals had political authority over their fiefs, and some even had Vassals of their own. This is known as subinfeudation.
Manorialism gave the Serfs the opportunity to be closer to their rulers, and possibly to influence the way their feudal Lord governed. If they did not like a particular tax or law, they might have taken it to their local Vassal, who may have taken it to his Lord in a meeting. However, the Serfs were not able to exit their contract of Serfdom with their Lord, so if they did not like the way a Lord ruled, they could not leave. Like any political system, feudalism and manorialism were not perfect. They did, however, provide something desperately needed by the local villagers, and that is protection.