The issuance of new currency and the patent of salt and iron respectively refer to the issuance of new currency: round square hole money is uniformly used throughout the country. The patent of salt and iron wine: the sale of salt and iron wine is strictly controlled by the imperial court and cannot be sold by private individuals. Qin Shihuang adopted the main methods of unifying the currency: first, the state unified minting, severely punished private minting, and placed the right to make currency in the hands of the state.