The ancient currency was mainly copper coins. Theoretically speaking, the value of copper itself is the value of copper coins, not what year and what words are written on copper coins. For example, a copper coin can't be the copper of the previous dynasty, but it won't be copper after the change of dynasty. Moreover, almost every regime change is often caused by cruel struggles and bloody wars, and the economy is seriously declining. Both the old and new regimes are in urgent need of money, and often, as for the new regime, it is also possible to gradually recover the coins of the former regime after it is stable, but the process is quite long. During the Yongzheng period of the Qing Dynasty, there were occasional Ming Dynasty copper coins in the markets in Zhejiang and Fujian, but the number was very small, and it was almost a hundred years since the Ming Dynasty died.