Feudalism is a system with a strict hierarchy with no upward mobility for serfs . Kings and nobles did own land that had serfs on them but it was not privatized in a libertarian sense. The king grants a portion of his land to nobles in exchange for loyalty. In order for it to be privatized in libertarian terms there would have to be a market transaction taking place. Feudalism was an enforced class system where as libertarians believe in a hierarchy based on merit. The feudal system violates the self ownership principle that is key to libertarian theory .