Technology
Weights & Measures
Emperor Qin may not have been nice, but he sure did take care of China! He standardized weights and measures in China. This made taxation possible and made for more efficient commerce. This may have also been used in the way of trading goods, none have ever confirmed such a thing---just a theory.
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Emperor Qin Shi Haung made it known that the Ban Liang coin (the round coin with a square in the middle) should be the coin used for all expenses dealing with money. They collected money from a string of coins.