 During most of their production, cash coins were cast, but during the late Qing dynasty, machine-struck cash coins began to be made.As the cash coins produced over Chinese history were similar, thousand year old cash coins produced during the Northern Song dynasty continued to circulate as valid currency well into the early twentieth century.In the modern era, these coins are considered to be Chinese “good luck coins”; they are hung on strings and round the necks of children, or over the beds of sick people.