What was early medieval feudalism like? As an example, Britain used to have five Kings... kingdoms were pretty small.

I've heard that knights had a lot more status in the early times, being more like an agent of the King (King Arthur style), rather than just part of a warrior caste. I'm not sure if that's true... but it seems that instead of heaving the Lords who serve the counts who serve the dukes who serve the barons, it was the King and a few Knights/Barons who served him.

Anyone know much about this subject?