Before the unification of China, city-states were independent from each other. The seven states Wei, Ch'u, Han, Ch'I, Qin, Wei and Chao emerged as key players in the fight for power. The City-state of Zhou and Shang were two of the most powerful state at that time. However, at around 500 BC the Zhou began to weaken and its states started warring each other. At this times nomadic tribes invaded the north of China leading most ducal states started to build walls along their boundaries This period was known as the “The Warring States Period” it did not stopped until the start of Ch’in dynasty where the unification of states happened. (Rocketman, E (2010) The Brief History of China nad the Great Wall Retrieve from
