The economy of China during the Song dynasty outpaced the supply of traditional coinage, leading the government to issue banknotes (Jiaozi (交子)) to increase the money supply. Subsequently, a government department was created to manage cash affairs, with its responsibilities including producing and issuing cash, and combating counterfeiting. The cash seal was developed as an anti-counterfeiting measure; official banknotes received a red, sometimes black or purple, stamp at their centres. This forced counterfeiters to attempt to replicate the seal, presumably leading to distinguishable lower quality stamps. Severe punishments, including the death penalty, were given to counterfeiters.
The use of cash seals is no longer restricted to governments. Seals or private individuals and organizations may be used in the same manner on private banknotes to represent the parties' trust, credit, or authority.
In the era of the Republic of China, these seal stamps could also be called Yinhang Yin (銀行印/银行印; direct translation: the seal stamp of bank, or just "bank seal").
In Japan, ginkō-in (Japanese: 銀行印) seals have similar functions.
^Minyi Daifang Lu (Waiting for the Dawn; a historic record): "... 上特设内宝钞局,昼夜督造,募商发卖,无肯应者。", recorded by Huang Zongxi in the Late Ming and Early Qing Dynasties