Japan, like all other places during the Middle Ages, was constantly changing their political, economic, and religious systems as well as keeping some things the same. Politically, Japan started out with a very centralized government, the only changes were the forms of centralized government over the years but for the most part it stayed the same; economically Japan started out with an agricultural society which morphed into a money economy due to the introduction of the metal coin, trade was still widely used all through the years and was dominant over coins until around the twelfth century; Japan started out with the worship of nature spirits which morphed into the Shinto religion, Buddhism took over around the eighth century. People saw no contradiction between the two religions and usually worshiped both Buddha and their nature gods.
Japan had a very centralized government in the beginning so that they could mount a strong resistance in the event of an invasion. Shitoku Taishi was a key figure in doing so and called for the creation of the centralized government. After his death, his successors reformed the government to make it more efficient. Even though he died, the idea of centralized government never changed. Around 794 CE decentralization was occurring because of the fail of taxation. A law code was introduced so that taxes went right to the central government and the farmland belonged to the state.
Japans economy started out as an agricultural society much like all places do. Although the land lacked the many they made it