The Title of Vassal developed as early as the 7th Century AD and was related to the practice of “Vassalage”. In this official “relationship” between a Ruler and a Lord – The Vassal would give his allegiance to a King or Queen. This allowed The Ruler to not only extend his power and control over a Region, but also gave Patronage from The Ruler to his Vassal. This Patronage normally extended to the owning of Lands (which were the original form of Medieval wealth).
Later, Vassals were expected to provide Fighting resources to his Ruler. This Vassals would train specifically for this function and were the first form of The Knight. Later, with control of Land, a Vassal might also have control over the Peasantry that lived and worked it. It was The Vassal’s responsibility to care for these people.
In some cases, Vassals were poor by Nobility standards. These “Lessor” Knights were associated under a Baron or Count, would counted them as his Vassals (with The Baron or Count being under a Vassalage to a specific Ruler). This form of early Feudalism was duplicated in many portions of The Medieval World, regardless of Culture. It would remain in place until the end of Vassalage around the 16th Century.