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This fascinating series of coins was made in Japan from Wado year 1 to Tentoku year 2 (708 AD to 958 AD), and formed the foundation for the currency used until the Meiji reforms in 1868. Interestingly, these coins are all modeled off of Chinese coins from the same time period; they are all round, cast, and display four characters on the obverse and none on the reverse. In Japan, these coins are referred to as "Kocho Juni Sen" (according to the Hartill catalog), which roughly translates to "Twelve Antique Coins," hence their name in English. All of these coins were cast in copper, with the exception of a few that were cast in silver, gold and iron. However, the purity (and size) of these "copper" coins varied wildly due to a "wave of Buddhism" (Munro catalog) at the time, in which the creation of thousands of statues of Buddha depleted the copper supply. Therefore, small and crude versions of these coins can be found that contain a wealth of other metals than copper (such as tin, lead and zinc). These coins have been heavily counterfeited since their release, so the collector must be very wary when purchasing them! Additionally, these coins are very rare nowadays, so they are expensive and difficult to locate, even in Japan. All in all, this captivating set of coins was the start of Japan's monetary system.