The Earliest Wall, Around 700 B.C.
The first wall was arguably built around seven centuries B.C. by the Chu State, powerful prince enfeoffed by the Zhou Kingdom and flourish during the Spring and Autumn Period (B.C. 770 ~ 476). Most scholars also believe that the Qi State, prince like the Chu State, also built its wall about the same time of the wall of the Chu State. Nevertheless, not until hundreds of years later did many other princes, known as warring states, involved in wars for subjugating each other, begin to build their own walls. This time was known as the Warring States Period (B.C. 475 ~ 221).
Warring States Period was a turbulent period, with alliance and breakaway, and restless battles between states arising from princes that annexed smaller ones and consolidated their rules for domination when the ruling power of the Zhou Kingdom (till 221 B.C.) was declining. In this background, the defense of one state against attack from others became significant. Because walls proved the best screen to chariots, main arms of that time, relatively powerful states, i.e. the Qin, Wei, Zhao, Han, Qi, Chu and Yan States, also known as "the Seven Powers", began to build walls along their borders. These walls are called pre-Qin Walls by historians today. And they are predecessor of the Great Wall.
The First Great Wall, Around 200 B.C., Length, 10,000 Li, i.e. 5,000 Kilometers
After the Qin Dynasty had established and unified the whole China in 221 B.C., the Emperor, i.e. the First Emperor, ordered to combine the walls constructed by the Zhao, Yan and Ex-Qin States, mainly to fend off the intrusion of the flying cavalry that made the Xiongnu in the north, and thus formed the first wall that exceeded 10,000 li or 5,000 kilometers. The Great Wall, short for the Great Wall of 10,000 li, thus had its name.
Three Great Walls
Many people know about the Great Wall. But maybe fewer know that there are actually three such Great Walls, the longest built during the Han Dynasty (206 B.C. ~ A.D. 220), following the Qin Dynasty, exceeding even 20,000 li. The Great Walls of the Han and Qin Dynasties still have remains, but most of them no longer exist. The Wall we see today was largely built during the Ming Dynasty (1368 ~ 1644). It stretches over 12,000 li from Jiumenkou near the Yalujiang River in the east, to Jiayuguan Pass in the west. By the Great Wall, people now usually mean the Great Wall of the Ming Dynasty. But in a broad sense, the term indicates one of the three Walls above.
In Chinese history, more than twenty states and dynasties built their own walls. Counted together, they come to a formidable length of 100,000 li.