Yan State coexisted with the other states during the Warrior States Period. Yan was constantly under attack by Qin, Zhao and the nomadic tribes. The sea in the east was its only natural protection. Two walls-North Wall and Yishui Wall-were built along the unprotected borders to prevent invasions.
Yishui Wall was built under the persuasion of a politician named Zhangyi to defend against Qin, Zhao and Qi states. The wall was located in what is today's Yixian County in Hebei Province, but few traces of it exist today. Search a Great Wall Tour
The North Wall was built in what is today's Liaoning Province. A famous legend was associated with the construction of this wall: Yan was under threat from a nomadic tribe called Donghu. A great general (Qinkai) was sent to Donghu as a hostage to maintain temporary peace between the two powers. Qinkai earned trust from the nomadic tribe and was set free later. He took advantage of knowledge gained during his captivity, attacked and forced Donghu to the far north. A wall was then erected to keep the nomadic tribe out.