The Great Wall of China has a long and complex history. It has been built and rebuilt for thousands of years.
China has a long history of wall-building. Private homes, villages, cities, and states had walls long before China was unified. During the Warring States period, the different states within China built walls to protect themselves from each other. Imperial China’s first dynasty, the Qin Dynasty (221 BC to 206 BC), was the first to attempt to build a wall a cross a large part of its northern frontier in order to defend against attacking tribes from the north. They built their Great Wall by connecting the parts of the Warring States walls that went across the northern border of China while destroying the other parts.
After the Qin Dynasty, each successive dynasty either continued building Great Walls or considered them unimportant.
Those dynasties that did build Great Walls often made use of existing walls, adding new sections in order to connect them together and reinforcing old walls where needed. Because of the vast size of China’s northern frontier, walls were built in what were perceived to be the most vulnerable areas rather than continuously from one end of the border to the other.
The Great Wall served many purposes:
To keep invaders out – The Great Wall was a psychological as well as physical barrier against invading military forces.
To serve as lookout posts – The elevated locations of the Great Wall and its towers enabled distant observation of invaders to provide the earliest possible warning.
To provide a communication and early warning system – Relaying from one watchtower to another using fire signals at night and smoke signals during the day, messages could be sent over long distances in a short time.
As an elevated roadway along the border – This enabled rapid deployment of personnel from one place to another.