What are the similarities between China and Japan?

Both states were closed for a long time. They were two separate worlds, two formed civilizations that for a long period of time did not feel much influence from the rest. Therefore, at the moment they are of great originality and interest. This also applies to unique historical information and writing with language. This isolation is due to its location in the very east of Asia and the large, sparsely populated space between China, Japan and other civilizations.