After Shang Dynasty collapsed, Zhou Dynasty began its administration in the history of China. The Zhou Dynasty can be divide into Western Zhou
( the middle of the 11th century B.C.- 771B.C.) and Eastern Zhou
( 770B.C.-256B.C). The Eastern Zhou Period has 2 period: The Spring and Autumn Period (770B.C.-476B.C.) and the Warring States Period (476B.C.-221B.C.).
During the 2,700 years history of China, ranging from the Eastern Zhou period to the Ming Dynasty (1368-1644), more than 20 states and dynasties were involved in the construction of the Great Wall. The Great Wall was initiated in the Spring and Autumn period and the Warring States period, It was built as a defense to prevent the invasion from other states and external tribes.
The Great Wall of the Chu State
The Chu State was located in the center plains at the lower reaches of the Yellow River. The Chu State was fairly slow in agriculture. However, it kept a powerful army and with it, Chu expanded its territory to the banks on the Changjiang River. It neighbored the Han, Wei, Song and Qi States in the north, the Ba and Qin States around the west, Bai'e in the south and a broad sea to the east. Its territory was the largest among the 7 Powers.
In light of historical records, the initial component of the Great Wall of China was constructed by Chu State. Chu State was a small prince that progressively developed by conquering weak states in the Spring and Autumn Period. To rule the roost in the Central Plains and avoid the intrusion from Jin and Qi states, Chu constructed series walls along its northern frontier in about 656BC. These boundary markers would gradually evolve to the Great Wall. The walls were shaped like the letter "U". The Wall of Chu was referred to as "the Rectangle Wall".
Entering the Warring States Period, Chu State extended its wall to defense the invasion from neighbor states especially the most powerful state --- Qin. And this is also the reason why the walls of Chu became more solid and integrated. You can still see the long- disintegrated walls at the site in the Lushan and Yexian Counties of Pingdingshan City, Wugang City, Fangcheng and the Nanzhao Counties of Nanyang City in Henan Province
The Great Wall of the Qi State
The capital of the Qin State was established in Linzi (the present Linzi county of Shandong Province). Qi neighbored the Lu, Chu and Song state in the south, the Zhao State in the west, The Yan State in the north. It was already a very powerful and large prince before the Spring and Autumn Period.
In order to prevent the invasion from other states, King Qi Xuanwang constructed a wall in the south part of the Qi state. The wall extended 500 km from west to east, connecting the bank of the Yuan River and the north foot of the Mount Taishan. It was the “Great Defense” that you can find in some historical literatures.