Warring States Period

• The state of Chu was the first to build a wall during the Warring States Period, which spanned more than 250 years from 476 BC to 221 BC. Shortly after Chu started, the other five states--Qi, Yan, Wei, Zhao and Qin--began to build similar walls.
  
  

Unification Period

• The Qin Dynasty was the first to rule over all China. Unifying the six regions into a single state, Emperor Qin was the first emperor of China. He ordered one of his generals to connect the walls of the six states, creating the Great Wall of China. The wall is called Wan Li Chang Cheng in Chinese, which translates as "The Long Wall of 10,000 Li" (a Li is a unit of measurement equal to a kilometer). The wall's main purpose was to protect the Qin Dynasty from the northern tribes.
  
  

Subsequent Dynasties

• During and after the Qin Dynasty, the Great Wall was extended, repaired and modified over nearly 2,000 years. Like the Qin dynasty, the Han Dynasty built a substantial extension to the Great Wall. The tribes to the north were nomadic and would simply move to a new location if their attacks were being stifled. The result of these extensions is a wall that is today 5,500 miles long.