Regarding the origin of flood memory, Mr. Wang Wei said in the article "The Main Harvest of the Source-seeking Project of Chinese Civilization": "Around 2000 BC, climate anomalies occurred in the middle reaches of the Yellow River, mainly manifested in temperature changes, especially uneven rainfall." According to this speculation, what Mr. Wang said is specific to the above areas, which is manifested in floods caused by a substantial increase in rainfall.
This view is more common sense. However, in the ancient literature on flood memory, there is no record of flood caused by other rainfall except Huai Nan Zi's "Heavy rain in Yu". On the contrary, I talked a lot about the drought in North China, and this drought memory is continuous and highly consistent. From the legend of the drought charm in the Yellow Emperor's era, to the myth that Houyi shot at the sun in the Xia Dynasty, to Shang Tang's preparation for self-immolation for rain, to a large number of rain divination in Oracle Bone Inscriptions, and to more recent historical records, the record of drought has never stopped. North China is mainly a dry farming area, and this memory is undoubtedly more historical and logical. Paleoclimate and environmental experts also believe that the precipitation in North China did not increase significantly more than 4,000 years ago, but showed a trend of substantial decrease.
Mr. Xu believes that the Yellow River flows out of the mountain hills and reaches the plain, which is flooded because of the great difference in terrain and no constraints, thus making the ancients in the Central Plains form flood memories. In other words, the memory of ancient floods in China mainly originated from river disasters in specific areas, and has nothing to do with precipitation. Archaeology tells us that the movement track of the main activity areas of the pioneers of civilization is generally from the hillside highlands to the open and low-level platforms and plains. In the middle and lower reaches of the Yellow River, for a long time after 5000 BC, the main centers of prehistoric culture distribution were concentrated in the highlands on the east and west sides of the North China Plain (then the North China lowlands). This area is mainly lakes and swamps. After the Yellow River flows out of the mountainous area in western Henan, there is no fixed channel and it flows freely. The present North China Plain is the product of long-term flood deposition of the Yellow River.
That is to say, the secondary platform mentioned by archaeologists is actually at the forefront of the huge lake formed by the flood of the Yellow River. In the process of their ancestors' migration to the lowlands, they will encounter an unheard-of real flood at some point. Although the flood has existed for a long time, people began to encounter it after leaving the hillside and coming to the platform. It is this unprecedented flood experience that created the prehistoric flood memory of the Chinese nation.
If we understand the nature of prehistoric floods, we will have a new perspective on ancient cities, water control and the origin of civilization.
The author thinks that when people come to the platform from the hillside and encounter floods, the most important thing to protect is their own residence, and the most effective solution is to concentrate on living, use the collective strength to build as strong a flood dike as possible around their residence, or dig a river ditch that is conducive to flood discharge at the same time. If these two are not enough, we need to fill the soil to raise the foundation of residential buildings, such as Pingliangtai ancient city in Huaiyang. Such a residence is the ancient city discovered by archaeologists now. At present, there is no specific data on the altitude of the cities in North China Plain during Longshan period, but it can be speculated that the cities in the same period should be at the same altitude, and the cities in the later period should be lower than those in the previous period, which was determined by the water level and its changes in the lowland lakes in North China at that time.
Therefore, Longshan Ancient City is a special settlement form invented by people to cope with floods, a bridgehead and base for people to develop lowland plains, and a product of the development of prehistoric agricultural society in China to a specific historical stage. The builder of the ancient city is the pioneer of agricultural civilization in plain settlement. Gun is probably the first expert who invented the technology of building cities. His great invention made people firm in the face of the flood. The record of "Gun Made" expresses the deep memory of his great achievements by later generations.
The purpose of people building cities in a new place is to cultivate the countryside. Because the city-building technology invented by gun has successfully prevented people's houses from being flooded, he or his successor will naturally do the same thing, trying to protect or cultivate new countryside by damming flood control, which is reclamation. But at that time, the reclamation was too advanced and ended in failure. He was punished for this, which should be a historical shadow reflected by the "flood" and a punished failure.
The lesson of Gun's failure inspired later generations, which made Dayu sum up the great invention of "spreading soil" and evolved into the legend of Dayu's water control recorded in later literature. Practice shows that digging ditches and cleaning waterways are effective ways to turn swamps into pastoral areas. That is to say, "Yu Fu laid the foundation stone", that is, "high and low, dredging rivers, leading to stagnation, and abundant water" in Guoyu's book. At that time, Dayu's main job was to dig the naturally formed small channels in the lowland swamp wider and deeper, accelerate the downward flow of water, and make the originally muddy swamp increasingly dry and easy to plant, which is what Confucius said. After hundreds of years or even longer of dredging, the flooded area of the Yellow River is decreasing day by day, making people's flood memory disappear, and the ancient city has completed its historical mission and been abandoned one after another. The disappearance of floods and the abandonment of ancient cities mean that the lowlands in North China have been developed to a considerable extent. This not only laid the core area of agricultural civilization in China, but also provided a geographical basis for the birth of Chinese civilization marked by the wide-area dynasty. At the same time, in the process of developing the lowlands in North China, the hillside residents who originally separated things met in the plain. It is this geographical foundation laid by the development of * * * and the historic encounter between the eastern and western nationalities that led to the birth and formation of Chinese civilization that began in the Xia Dynasty, and made the eastern and western nationalities with different cultures increasingly merge into a unified Chinese nation.
In the Western Zhou Dynasty and the Spring and Autumn Period, "spreading soil" seems to be insufficient to show its greatness and wisdom. At this time, all kinds of water control irrigation, including canal digging, became possible and necessary, and Dayu was naturally known as the hero of water control in the era of irrigated agriculture. The interpretation of the story of water control restored Dayu's great image as a pioneer of the Chinese nation. The legend of Dayu's water control has precipitated the great course of how the Chinese ancestors developed the swampy lakes with low water and low humidity and the flooded areas of the Yellow River into the Woye Plain in North China. The word "water control" can never cover Dayu's real contribution to lowering the hilltop and building China.