 If one used movable type to produce multiple copies of the same document, the speed of printing would increase relatively.At least 13 material finds in China indicate the invention of bronze movable type printing in China no later than the 12th century, with the country producing large-scale bronze-plate-printed paper money and formal official documents issued by the Jin (1115–1234) and Southern Song (1127–1279) dynasties with embedded bronze metal types for anti-counterfeit markers.Such paper-money printing might date back to the 11th-century "jiaozi" of Northern Song (960–1127).