The beginning of the consumption of the Great Wall can be traced back to the 9th century BC in the Zhou period, Qin Shi Huang, the first emperor of the Qin Dynasty, ordered to begin the construction of a great wall, under which project the long walls in the north of the former Qin. Back in the Warring States Period, to strengthen defense against each other, the princedoms built massive walls on their borders and linked series of walls and beacon towers into continuous lines, hence the name “Great wall.” As they differed in the area of territory, their defensive walls varied in length. Long walls were constructed in the Northern Wei and Sui periods, as recorded in ancient texts. During the Ming period, When all the walls built by numerous princedoms in the Spring-Autumn and Warring States Period and later by various dynasties over a span of two millennia were linked together, the Great Wall would come to the grand total of well over 50,000 km in length— a marvelous engineering feat in human history!