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 * Great Wall of China has been dated back to the 4th century, construction started in 3rd century
 * Great Wall of China was 10 to 15 meters high and 2500 kilometers long
 * The barrier was built to keep the Mongols and other foreing influences out of China
 * MIng state restored the system of civil service examinations
 * MIng weakened because of pirates and smugglers during the 1520s through the 1560s