From ancient times to the present, there have been regional divisions in successive dynasties. For example, the Western Zhou Dynasty was divided into various vassal States, and the Qin Dynasty implemented the county system. In the Han dynasty, the county system and the vassal state system were in parallel, while in the Tang dynasty, the county system was only the geographical division of the evolution of the Qin county system.

And now we have Henan, Hebei, Hunan, Hubei, Shandong and Shanxi. These names have existed since ancient times. What is their river now? What lake? What mountain is the boundary? Let's start with Henan Province and Hebei Province. The river between them refers to the Zhanghe River. In historical records:

During the Northern Song Dynasty, Bao Zheng suggested that Song Renzong ask people to reclaim the land on both sides of the Zhanghe River. Song Renzong was overjoyed at Bao Zheng's suggestion and agreed. Both sides of the Zhanghe River are fertile fields, which are the main grain producing areas in the Northern Song Dynasty, supplying the capital of the Northern Song Dynasty with grain.

Zhanghe River is a tributary of Haihe River Basin in northern China, which was called Zhangheng and Hengshui in ancient times. Zhanghe River originated in Changzhi City, Shanxi Province, and the upper reaches of Zhanghe River are composed of Qingzhang River and Zhangzhuo River. The lower reaches of the Zhanghe River separate Henan and Hebei provinces and become the boundary river between Henan and Hebei.

Zhanghe River has a long history. During the Spring and Autumn Period and the Warring States Period, Ximen Bao built the Ximen diversion canal in Linzhang section of Zhanghe River. At that time, when Ximen Bao served as Yecheng Order, he saw that the local land was barren because it could not be watered. Ximen Bao mobilized local people to develop aqueducts to irrigate farmland.

Since then, Yecheng has become a fertile land, and the people have worked hard to develop Yecheng into a granary. Ximen Bao led the people to dig twelve canals, that is, to inject water from the Zhanghe River to ensure farmland irrigation. Zhanghe River flows eastward along the junction of Hebei and Henan provinces, and then replaces the Yellow River as the boundary river between Henan and Hebei.

And which lake is separated from Hunan and Hubei? In ancient times this lake was called Yunmengze. When Yun Mengze is mentioned, many people will think of Han Xin. After Han Xin helped Liu Bang conquer the world, he was made King of Chu, guarding the fief of the former Chu. Han Xin's men will be numerous at this time, and Liu Bang is afraid of Han Xin and wants to cut off the relieving of Han Xin. In the record:

Liu Bang took the advice of Chen Ping, a counselor, and said to his ministers, "I want to swim in Yunmengze, and please accompany my ministers." Han Xin thought that Liu Bang was really traveling and came to Yunmengze to accompany him. Finally, he was arrested by the China army in ambush, placed under house arrest in Chang 'an and demoted to Huaiyin Hou. Liu Bang put Han Xin under house arrest in Yunmengze, and he was carefree from then on.

Yunmengze, a lake that has appeared many times in history, is actually an ancient lake group on Jianghan Plain. Yun Mengze, called "Yunmeng Ozawa" in ancient times, was measured in the pre-Qin period, with a circumference of about 450 kilometers. Jianghan Plain is low-lying, criss-crossing with rivers and dotted with lakes.

The river flows through this place, forming lakes of all sizes, and then converging into Yunmengze Lake. Later, with the neotectonic movement in Jianghan area, the terrain began to tilt from north to south, and the area of Yunmengze gradually narrowed. Dongting Lake, which we see now, is a lake formed by the backward flow of Jingjiang River, gradually replacing Yunmengze's position.

Now when we say boundary lake between Hunan and Hubei, we mean Dongting Lake, but in ancient times it means Yunmengze. Which mountain separates Shandong from Shanxi? In fact, ancient Shandong and Shanxi are not what we said today. During the Spring and Autumn Period and the Warring States Period, there was a saying that it was "the six countries of Shandong".

We were surprised to hear that. Isn't Shandong the land of Qilu? The two most important countries are Qi and Lu. Why is it called "Shandong Six Countries"? In fact, it is because of the different standards of regional division. During the Spring and Autumn Period and the Warring States Period, "Shandong Six Countries" refers to the six countries east of Lushan Mountain.

Shanxi refers to the state of Qin west of Lushan. At that time, Qin was close to the Rongdi tribe, and the folk customs were tough. The six countries of Shandong were ashamed of being in the same Qin Dynasty, so they pretended to be divided. In the end, Qin made great efforts to rule and destroyed the six countries. In history, there are also records about Lushan Mountain:

This is the record of Lushan Mountain in the Eastern Zhou Dynasty, and it is also the boundary between Qin and Shandong. Xiaoshan Mountain is a branch of Qinling Mountain, which is connected with Huashan Mountain in the southwest, and cut off by Hongnongjian Valley and Luohe Valley in the northwest and southeast respectively. Today we are talking about Shandong and Shanxi. The dividing line between them is Taihang Mountain, also called "Five-Star Mountain".

Taihang Mountain is located between Shanxi Province and North China Plain, spanning four provinces, reaching King Wu in the south and Shanxi Plateau in the west. Today, the regional division of Shanxi and Shandong is bounded by Taihang Mountain.