Mumonginsen

Mumon ginsen (無文銀銭) (aka "Plain silver coin") is believed to be the earliest form of Japanese currency.

Throughout their search history stretching back to the Enkyō period, about 120 Mumon ginsen have been excavated from 17 sites: seven in Yamato, six in Omi, and one each in the Settsu, Kawachi, Yamashiro, and Ise regions.

[1] Only a few of those excavated have inscriptions, and many of the coins have silver pieces attached to their surfaces which are thought to have been added to make the weight uniform.

Professor Fumio Tanaka (Waseda University) mentions that in Silla, Baekje, and Goguryeo, the use of gold and silver was regulated by royal authority.

As each powerful clan (chief) obtained these precious resources, there was a basis to circulate coins in a multilateral manner without being regulated by the royal authority.

(see: "Excavated examples" section below)[9] Japanese archaeologist and professor Keiji Matsumura points out that the remains at the ruins sites (where the coins were found) has generally been either discarded or deliberately buried.