Is the melody part of real Chinese classical music not handed down?

The ancient people only copied the music books by hand, and the number was small. After so many wars and migrations in history, most of them must have been lost. The songs of Chinese style mostly adopt the theme of "Gongdiao". The names of the five tones are: Gong, Shang, Jiao, Zheng and Yu. The mode with Gong Yin as the main tone is called Gong Mode. Drink do re mi so la separately. I remember a program in which Tayu Lo talked about this, and said that his "Laughter at the Sea" composed for "the legendary swordsman" used the five tones of Gong, Shang, Jiao, Zheng and Yu. You can listen to it. ^_^