The great wall was build by several Emperors over a long period of time. It it believe to have started in the 7th C BC. It was then further fortified between 5th C BC to 221BC by the states of Qi, Yan and Zhao. It was then extend by the first Emperor Qin in ca 221 BC. Down through the years other dynasties have build extensions else include Han, Sui, Northern, Jin, Ming and Qing.
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