Lintao County, Gansu, China
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History.com[3] and the Qin dynasty's Wikipedia[2] entry date Qin Shi Huang's order to join the northern border walls into one system to around 220 BCE, without a more precise date surviving.Around 220 BCE, China’s first emperor ordered the rival kingdoms’ old border walls linked into one defensive line, the earliest version of what became the Great Wall.
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