 After the introduction of a unified currency system in 1889, cash continued to be used as a subunit of the yuan with 1000 cash being equal to one yuan.Coins continued to be denominated in cash until the 1920s nationally and for a time thereafter regionally.Cash ("văn") was a currency unit for copper coinage in Vietnam until the introduction of the French Indochina piastre in 1885 when it became a sub unit of the piastre usually known as a "sapèque".