Four seas: the geographical concept handed down from ancient Confucianism, which means that the whole world belongs to China; Outside of China, it's everywhere. The author of Shan Hai Jing thinks that the four seas are "within the sea", and there are five mountains in the sea, but there is nowhere in China. Beyond the four seas, there are "overseas". Beyond the "overseas", there is a "great famine", where the sun and the moon go in and out, and between the "overseas" and the "great famine", there are many countries and mountains. The name "Sanjiang" was first put forward by the works of Shangshu in the Warring States Period (475 BC-22 BC1year). There is an article "Gong Yu" in Shangshu, which describes the territory, geology, property, tribute, transportation, politics and ethnic distribution of Kyushu (that is, the whole country is divided into Hebei, Yanzhou, Qinghai, Xu, Yang, Jing, Henan, Liang and Yongjiu). It is the earliest important work of human geography in China. The book introduces the geography of Yangzhou (one of Kyushu, generally referring to the Yangtze River Delta region in the lower reaches of the Yangtze River today) as "Three rivers will enter immediately, and the earthquake will be fixed." The "three rivers" mentioned here mainly refer to the Yangtze River, the Yellow River and the Huaihe River, because most of the Yangtze River Delta region is a plain below 50 meters above sea level, and these plains are mainly alluvial from the Yangtze River, the Yellow River and the Huaihe River. In feudal society, Zhou Li, one of the "Thirteen Classics" (i.e. 13 ancient books) textbooks that feudal rulers must read, was regarded by ancient scholars as the Duke of Zhou (BC 1 1 century). Zhou Wuwang died two years after the establishment of the Western Zhou Dynasty, and his son became the young king, and Duke Ji Dan succeeded to the throne, which made an important contribution to the consolidation and development of the Zhou Dynasty. When a king grew up, the Duke of Zhou regained power and became king. Contemporary literature and classic scholars identified Zhou Li as a work of the Warring States Period from bronze inscriptions unearthed in Zhou and Qin Dynasties. Zhou Li's Local Records of Xia Guan called Yangzhou "Southeast Yangzhou" ... and its three rivers are in Sichuan. This refers to the topographic features of ancient Yangzhou rivers criss-crossing and dense as a net, which is the same as the expression of "Three Rivers" in Gong Yu. After the history entered the Han Dynasty, the name of "Sanjiang" had many interpretations. During the Eastern Han Dynasty (AD 25-220), the famous historian Ban Gu wrote China's first masterpiece of dynastic history, Hanshu, following the Historical Records written by the historian Sima Qian in the Western Han Dynasty (AD 206-23). Geography of Hanshu takes the Yangtze River between Wusong River in Anhui Province and Wuhu City and Yixing City in Jiangsu Province to connect Taihu Lake, and the lower reaches of the Yangtze River are called the "Three Rivers" of Nanjiang, Zhongjiang and Beijiang. Zheng Xuan, a native of the Eastern Han Dynasty, once wrote "Notes on the Rites of Zhou", arguing that Nanjiang should be the Ganjiang River (which runs through present-day Jiangxi Province, with a total length of 864 kilometers, flows through the three great basin cities of Gannan, Ji 'an and Poyang in Jiangxi, and flows into Poyang Lake, the largest freshwater lake in China). Zhongjiang should be the Minjiang River (originating from Minshan, connected with Sichuan, Gansu and Shaanxi, with a total length of 7 1 1km and a drainage area of 166084 square km, Yibin City, Sichuan Province was renamed the Yangtze River after joining the Jinsha River); Beijiang River should be the Han River (also known as Hanshui River, which originates in the west of Shaanxi Province, with a total length of 1.532km and a drainage area of 1.6885 1 km2, and is the longest tributary of the Yangtze River, which flows into the Yangtze River in Wuhan). Sheng Hongzhi put forward his views on the "Three Rivers" of Nanjiang, Zhongjiang and Beijiang in Han Geography Elementary Book, and quoted Zheng Xuan's views. He wrote in Jingzhou Ji that the upper reaches of the Yangtze River are Nanjiang, the middle reaches of the Yangtze River are Zhongjiang, and the lower reaches of the Yangtze River are Beijiang, which are collectively called "Sanjiang". During the Northern Wei Dynasty (A.D. 386-534), the famous geographer Li Daoyuan (A.D. 466-527) paid great attention to looking for historical sites in various places, observing the distribution of rivers and waterways and the appearance of various regions, and made comments on the Notes on Shuijing, which were made by predecessors. After years of hard work, I finally wrote a famous geographical work-Annotation of Water Mirror, which is 20 times as rich as the original, quoting more than 430 kinds of ancient books, and recording in detail the direction of 1252 rivers and the mountain cities that passed by. It has important literary and historical value and is a masterpiece of ancient geography in China. According to the Notes on Water Classics, the "Three Rivers" recorded in Geography of Han Dynasty should be divided into three rivers (which are said to flow eastward from Guichi City, Anhui Province to Yuyao City, Zhejiang Province, but actually a non-existent waterway), Zhongjiang River (which refers to the Yangtze River leading to Taihu Lake) and Beijiang River (which flows from the lower reaches of the Yangtze River to the sea). Guo Pu (Guo Jingchun) of the Jin Dynasty was quoted as saying that Minjiang River, Songjiang River (now Wusong River) and Zhejiang River (now Qiantang River) are "three rivers". According to the historical book "Wu Yue Chun Qiu", Zhejiang (Qiantang River), Pujiang (puyang river) and Tongjiang (Cao E) are also called "Three Rivers". Notes in Zhao Wei Putonghua: Songjiang (Wusong River), Qiantang River and puyang river are "Three Rivers". Selected Works of Gong Yu quotes Gu Yi's Wu Di Ji: Songjiang, Loujiang (Liuhe) and Dongjiang (blocked) are the "Three Rivers". Huayang County Records compiled by historians in the Western Jin Dynasty is a pioneering work in the history of local chronicles compilation in China, and it is also the earliest and relatively complete local chronicles in China. The National Records of Huayang named Minjiang River, Fujiang River and Tuojiang River in the upper reaches of the Yangtze River as "Shu Sanjiang". Yang Shen, a writer in the Ming Dynasty, tried to be the top scholar and was named Hanlin. Because he angered the emperor, he was imprisoned in Yongchangwei, Yunnan for 35 years and finally died in Yunnan. Yang Shen has a wide range of knowledge and more than 0/00 kinds of writings, leaving a precious cultural heritage for future generations. The evaluation of Yang Shen in Ming History is "knowing clearly, making wealth, being cautious first." His book Sick Bed Handman calls Minjiang River as the outer river, Fujiang River as the middle river, Tuojiang River as the inner river, and the outer, inner and middle rivers are collectively called "Shu Three Rivers". The History of Chinese Historiography proves that Gong Yu is the earliest important work of human geography in ancient China, and Shan Hai Jing is the earliest masterpiece of physical geography in China. Shan Hai Jing is an oral legend, written in the Warring States and supplemented in Qin and Han Dynasties. This volume *** 18 mainly describes the mountains and rivers (550 mountains and more than 300 waterways), situation, soil, strangeness, historical sites, nationalities, products, witch doctors, sacrifices and other primitive places in 40 ancient countries such as Ba, Shu and Chu. Guo Pu said that the Yangtze River, Xiangshui (i.e. Xiangjiang River, which originates from the western foot of Haiyang Mountain in the northeast of Guangxi Zhuang Autonomous Region, with a total length of 8 17km and a drainage area of more than 80,000 square kilometers, is the river with the widest drainage area and the highest economic value in Hunan Province, and flows into Dongting Lake) and Yuanjiang River (which originates from Wu Yun, Guizhou, and runs through the southwest and northwest of Hunan, with a total length of 10). Shan Hai Jing Hai Nei Dong Jing supplemented by the Western Han Dynasty is called Dajiang (Minjiang), Nanjiang (Neijiang) and Beijiang (Fujiang) "Minjiang". In the records of Yuanhe County in the Tang Dynasty, Minjiang River, Lijiang River (also known as Lishui, which is mainly composed of Lishui, Laishui and Lishui in the northwest of Hunan and flows into Dongting Lake) and Xiangjiang River are collectively called Xijiang, Zhongjiang and Nanjiang. During the Ming and Qing Dynasties, the Lijiang River (the upstream name of Gui Jiang, a tributary of the Xijiang River in the Pearl River system), the Zuojiang River (originating in the foothills of northeastern Vietnam and a tributary of the Yongjiang River in the Pearl River system) and the Youjiang River (originating in the foothills of southeastern Yunnan and crossing Nanning after joining the Zuojiang River in Laokou Town, Nanning, Guangxi) in Guangxi were called "Three Rivers". This "three rivers" is the opinion of ancient people concerned. Since modern times, people have gradually realized that the positioning of these names of "Three Rivers" is far-fetched, which is mainly influenced by historical factors such as the limitation of social and historical times, the difficulty of transportation, the closure of regional culture and the limitation of personal knowledge and experience. Nevertheless, it is still the tireless exploration of the name of "Three Rivers" by people of insight in ancient times. It can be said that this kind of exploration of ancient ancestors undoubtedly left the "Three Rivers" valuable cultural and spiritual wealth to future generations. So far, experts and scholars in the field of history and geography really can't make a fixed conclusion on the name of "Three Rivers", because there are many rivers in China, and the topography of high in the west and low in the east makes all the rivers run down, "One Jiang Xiangdong Stream", and most of the rivers flowing out belong to the Pacific water system. By tracing the historical and geographical knowledge of the name "Sanjiang", we can make such an understanding of the name "Sanjiang", and take this understanding as the conclusion of this paper: "Sanjiang" is not a fixed name of Sanjiang, and there is no specificity of natural and administrative attributes of the basin; "Three Rivers" should be the general name of many rivers and waterways in the outflow river system. This understanding is conducive to the inheritance and promotion of Chinese culture by contemporary Chinese sons and daughters, and avoids unnecessary academic disputes over the particularity of the name "Sanjiang"; Children of the "Three Rivers" in any water system can know, love and build the "Three Rivers" that have provided the most selfless dedication for Chinese descendants from generation to generation according to the origin of history and the continuation of history in reality. Only by understanding, loving and building the "Three Rivers" can we truly form a new picture of economic prosperity and building a harmonious society in an all-round way.