Gu Jiegang's Ancient History of China Caused by Layers. There are three main contents. First, "the longer the time, the longer the legend period of ancient history". For example, the oldest person in the Zhou Dynasty was Yu, Yao and Shun were born in Confucius, Huangdi Shennong was born in the Warring States, and Huang San was born in Qin. Only after the Han Dynasty did the so-called "Pangu" create the world. Gu then formed a hypothesis: "ancient history is made up of layers of accumulation, and the order and arrangement system of occurrence are just the opposite." Second, "with the passage of time, the central figure in the legend is getting bigger and bigger." Third, when exploring ancient history, even if you can't know the true state of something, you can know the earliest state of something in the legend. For example, "we can't know the history of the Eastern Zhou Dynasty, but at least we can know the history of the Eastern Zhou Dynasty during the Warring States Period; We can't know the history of Xia and Shang Dynasties, but at least we can know the history of Xia and Shang Dynasties in the Eastern Zhou Dynasty. " A general conclusion drawn by Mr. Gu is: "We should distinguish ancient history, despise the arrangement of historical sites and pay more attention to legendary experience." Later, he simply told the whole story of his knowledge orientation: "My main point of view on ancient history is not its truth but its changes." In short, it is "if you don't build summer, poverty will change."