Those who have seen classic films such as hero, Troy and the Lord of the rings will be shocked by those tragic siege scenes. Because if the city wall is broken, it means that the city is lost and the soldiers left behind will end up in a tragic end.
Whether in China or in foreign countries, ancient cities have walls. So, how did the city wall develop and change? We can imagine that at first, human ancestors just learned to make and use stone tools, wooden sticks and tools for drilling wood for fire. They also learned to build huts in trees or dig caves in the ground. In order to prevent the invasion of wild animals, they will build fences or fences with materials such as trees and stones. Later, people living in groups formed different small societies. In order to distinguish territory, they would guard against each other and build similar fortifications. Thus, the city wall, the earliest symbol of the city, appeared.
The Chinese character "city wall" refers to both the ancient Chinese city wall and the ancient Chinese city wall. Because in ancient times, most cities had to build the city wall first, and the city river had to be built outside the city wall. The earliest city walls mainly played a protective role. The ancient people used cold weapons such as swords to attack or defend the city, and the city walls played an effective role in defending the enemy. Moat is actually a manually excavated trench filled with water. It can be used as a barrier for the city wall. The city wall is the separation between the inside and outside of the city.
It can be imagined that when the city wall first appeared, there must be a small group of people living in the city. They traded with another group of people outside the city, so the market must be outside the city. But later, with the continuous improvement of the city's equipment, the transaction was transferred to the city, and the "city" was formed in this way, so the term "city" later mainly refers to doing business in the city.
With the development of the city, only one wall is not enough to protect the city. Moreover, with the wall, the princes and nobles can be separated from the common people. For example, the ancient book "Wu Yue spring and Autumn Period" (lost text) once had such a description: "build a city to defend the king, build a Guo to live in people." What is a city? What is Guo? Originally, the city is bounded by walls. The city is also divided into inner city and outer city. The inner city is called city and the outer city is called Guo. There are high officials of the emperor in the inner city and civilians in the outer city.
For example, there were four walls in Beijing in the Ming and Qing Dynasties. The innermost one was the feudal imperial palace surrounded by the walls of the Forbidden City, which is still intact, known as the palace city; Further out, the imperial city wall enclosing the Forbidden City and its surrounding palace service area; Then to the outside, there is the inner city where only flag people were allowed to live in the Qing Dynasty, and then the outer city where ordinary people lived.