 Since then however, the shell has become a symbol for money in many Chinese and Japanese ideograms.The earliest coins to reach Japan were Chinese Ban Liang and Wu Zhu coins, as well as the coins produced by Wang Mang during the first centuries of the first millennium AD; these coins have been excavated all over Japan, but as Japan's economy was not sufficiently developed at the time, these coins were more likely to be used as precious objects rather than a means of exchange; rice and cloth served as the main currencies of Japan at the time.The first coins produced in Japan are called the "mumonginsen" (無文銀銭, or 'silver coins without inscription') and the copper alloy "Fuhonsen" (富本銭, coins made from an alloy of copper, lead and tin) which were all introduced in the late seventh century.