Something isn't quite right here, I agree. From the BBC:
"Paper currency was first used in China as early as AD 1000. However, the Ming were the first Chinese dynasty to try to totally replace coins with paper money. The state issued too much paper money, however, causing hyper-inflation. By 1425 paper money was worth only a seventieth of its original value and the use of paper currency in China was suspended."
http://www.bbc.co.uk/ahistoryoftheworld/objects/F3oFoFDuTx-r..."Eventually, around 1425, the Chinese government gave up the struggle and suspended the use of paper money. The fairies had fled, or, in grander language, the faith structure needed for paper money to work had collapsed. Silver bullion would now be the basis of the Ming monetary world."
http://www.bbc.co.uk/ahistoryoftheworld/about/transcripts/ep...According to one book, the "transition to a silver ecoomy" (i.e. silver coins) lasted between 1000 and 1435; it's the only time I've seen that number used.