Tang Dynasty used not-weighted currency "Kai-yuan tun pao" (開元通寶) instead of traditional currency system "Wu-chu" (五銖) Therefore, from then on, Tang got troubled in definition of "Bad Money" (惡錢) because there was no guarantee about currency weights on the surface of coins. Tang people had no guide-line to define Bad Money but follow the former historical experience. However, these definitions in history had no consistency, and differed in variation. For example, "Bad Money" was classified into "Bad Abused Money" (惡濫錢), "Old Money" (古錢), "Vernacular Money" (民鑄錢),and "Thief-made Money" (盜鑄錢) Some emperors allowed people to use Old Money and Vernacular Money. Some allowed people to use less-weighted Bad Abused Money, and some only made legal of contemporary new-made money no matter it was made by government or ordinary people. Even worse, some emperors never make new money but only allowed Old Money currency. Varieties of currency policies forced Tang Dynasty had to discover its own financial laws like the blind headed into the dark. This article will find out real examples to research Tang's arguments in defining Bad Money. In additions, the reasons for the appearance of Bad Money are also included as an important issue in this article.
