Dikes and irrigation in Ningxia trace to the beginning of dynastic rule , when the Qin rulers who unified China in 221 B.C. built irrigation for soldiers garrisoned on some of the earliest sections of the Great Wall .
Ningxia /location/administrative_division/country China
China /location/location/contains Ningxia
China /location/country/administrative_divisions Ningxia
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Ningxia
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China
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China
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Ningxia
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China
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Ningxia
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