In the world of bartering, you can only obtain a goods by exchanging it with other goods. Which mean that your option for occupation would be limited to a producer for a certain goods.
In a world with money, you don't have to do that. You can choose occupation that is not related to production (such as painters, singers, or Teachers) and in exchange for your work, you can obtain money to buy the goods that you need.
King - The top leader in the land was the king. The king could not control all of the land by himself, so he divided it up among the Barons. In return, the Barons pledged their loyalty and soldiers to the king. When a king died, his firstborn son would inherit the throne.
