The idea came accidentally. A Szecuan mint could not get enough metal to make more coins, and the demand for coins had rose as the numbers shrank. The official of coinage, Chang-ho, was a bit nervous and anxious about what to do. He decided to present a certificate signifying the value in silver. The certificate would be used until enough metals could be circulated again as coins. Scribes gave each piece of paper a value and it was officiated with the seal of the province.
During the Ming dynasty (1368-1644 A.D.) money was printed on gray paper to fool forgers. The Mandarins had suggested to put the hearts of the writers to be smashed into a pulp and added into the mixture to make money. Not wanting to lose his writers, Emperor Wu searched for another way. His consort advised him to let their works be pounded in with the pulp to make paper money out of it. The black ink of the characters now were a dark gray.
The Chinese also encountered many types of paper money troubles, including inflation and currency reform.
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