Why are many China traditional cultures passed down in Japan but lost in China?

Because Japan's geographical position determines that it is rarely impacted by civilization in history, a little civilization can be introduced into it to have a long-term and stable natural growth environment. So it is a well-preserved peach blossom garden with ancient structure.

China's geographical position is just on the edge of Eurasia civilization, which determines that it has suffered the biggest fluctuation of civilization impact in history. The foundation of civilization has not been able to grow for a long time and has been washed away by new social trends, so culture has never had a solid carrier in China.

It's like if you live in a remote mountain village, after a popular culture is introduced into your village, you can preserve it for a long time without being influenced by the outside world and play it beautifully. However, if you are in the suburbs of the city, pop culture will spread to you from the city center. If you don't wait to catch up with the trend, you are behind the times, and you have to catch up with the new trend in a hurry. In the end, you will learn nothing.