Also known as the 12 Ancient Coins of Japan, this captivating set of cast coins was the start of Japan's monetary system. Made starting with the Wado Kaichin in Wado year 1 (708 AD) and lasting until the Kengen Taiho in Tentoku year 2 (958 AD), this set of coins formed the foundation for the more commonly known Kanei Tsuho coinage that was used until machine struck the Meiji reforms in 1868. Most of these coins are modeled off of Chinese coins from the same time period. In Japan, these coins are referred to as "Kocho Juni Sen" (according to the Hartill catalog), which roughly translates to "Twelve Antique Coins." All of these coins were cast in copper, with the exception of a few special issues in addition to the regular coins 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" (according to the Munro catalog) at the time, in which the creation of thousands of statues of Buddha depleted the copper supply. Hence, small and crude versions of these coins can often be found that contain a wealth of other metals than copper (such as tin, zinc and even lead). These coins are rare and have been heavily counterfeited since their release, so collectors must be very wary when purchasing them.