In many ancient Chinese poems, "Yunmeng" or "Yunmengze" is a frequent noun, which refers to a lake and marsh area that once existed in the Jianghan Plain in the pre-Qin period, and gradually disappeared after the Han Dynasty, so that it is difficult to determine its scope and specific form later. Of course, the literati's "Yunmengze" has actually evolved into a magnificent and fantastical image, used to symbolize the obscurantist but mysterious beauty of ancient times. Many people often confuse "Yunmengze" with Dongting Lake, or think that the latter is a remnant of the former. In fact, the two are in the north of the Yangtze River and the other in the south of the Yangtze River, so they should not be related.
In the Spring and Autumn Period and even earlier, the entire low-lying area in the south, including the Jianghan Plain, was densely populated with lakes and marshes, coupled with sparse population and a very low degree of development, so it was regarded as a wild land by the Central Plains Zhuxia. At that time, there was no such thing as "Ze" or "Yunmengze", because people were only gathered in a small number of settlements in these places, and they were absolutely disadvantaged in the face of the harsh natural environment. However, the will of human beings to expand their living space was strong enough, and they continued to build dikes, block the water of the lake, and drain the swamps, and after hundreds of years of development, by the middle and late Warring States period, the scope of the lake and marsh area had been greatly reduced, and the outline of many lakes in later generations was initially revealed.
The so-called "dream" is the spoken language of Chu recorded by the Central Plains people, which means the lake. The "cloud" refers to the area of the ancient Yun Kingdom, roughly near Anlu in present-day Hubei. "Ze" refers to both swamps and shallower lakes. "Yunmengze" is also said to be very late, and this statement is usually a general rather than a real reference, that is, a collective name for the lake and marsh groups in the territory of the Chu State, rather than specifically referring to a specific lake. In other words, it is very likely that there was no such a big lake called Yunmengze in history, it is just the general name of the Chudi Lake by the Central Plains.
Mr. Tan Qixiang, a famous historical geographer in China, has also put forward a hypothesis, that is, "Yunmeng" and "Yunmengze" are actually two concepts: the former refers to a large special safari area of the King of Chu, while the latter is a large lake in this area. The reason for this is that in the literature since the Qin and Han dynasties, when the term "Yunmeng" is mentioned, it is often associated with the safari activities of the Chu king and the nobles of the Chu State. The safari area called Yunmeng is extremely extensive, involving both south and north of the river, including not only many lakes, but also endless mountains, forests, fields and urban settlements. The Chu people frequently hunted in such a place with complex terrain and vast territory, and also had the intention of exercising martial arts, will, and strengthening the organization of the army.
His hypothesis is a bit too far-fetched, and I am afraid that it will be difficult to confirm it with more literature and archaeological excavations. At present, most of the opinions of scholars still believe that "Yunmengze" is either a general term for lakes and marshes in the Jianghan Plain, or a large lake specifically referring to the place "Yun". In any case, this once vast and mysterious and wild Yun Mengze has long since ceased to exist. After the Qin and Han dynasties, immigrants from the Central Plains migrated to the south in large numbers, bringing with them more advanced agricultural production techniques and deepening local development. After arriving in the Jin Dynasty, the denser and denser population made people have to ask for land in lakes and marshes, and the "Yunmengze" or a large area of primitive wetlands that once existed in the south gradually disappeared ......