 Ancestor coins () also known as "engraved mother coins" () were introduced around 1730 during the Qianlong period in middle of the eighteenth century to improve the quality control of mother coins, these ancestor coins were used to cast more mother coins and from a single ancestor thousands of mother coins could be cast.The production process of making mother coins with ancestor coins was the same as it was for the casting of circulation coins from mother coins, however these coins were usually only produced for a new reign title, when preparing to cast new cash coins with new inscriptions for a recently ascended emperor, a mint would first engrave an ancestor coin out of fine brass which would form the basis for mother coins.The introduction of ancestor coins under the Manchu Qing dynasty lead to all mints having more consistently produced coinages and smaller variations between the coins produced by separate mints in both inscription (or legend) as well as in quality.