Entering Hangu Pass, I encountered a performance held by a middle school, and the students were full of vigor. Back then, Laozi passed through Hangu Pass and was entangled by the pass commander Yin Xi. He had no choice but to write a 5,000-word article to get it over with. As a result, it was regarded as the "Tao Te Ching" by you, and regarded as a classic by Taoism. Hangu Pass was also regarded as the source of Taoism.