Kōchō Jūnisen — The Dream and Reality of the Ritsuryō State

In 708, during the reign of Empress Genmei, Wadōkaichin was minted. This was a groundbreaking attempt aimed at establishing a monetary system by the state. Nara-period Japan aimed to model itself as a centralized state after China’s Tang dynasty, and the introduction of a monetary economy was part of this effort. The minting of Wadōkaichin was carried out by the Mint Bureau established in Yamashiro Province (now Kyoto Prefecture), where contemporary craftsmen painstakingly created each piece using copper-based alloy. Initially, an exchange rate was set, where 100 coins could purchase one koku (approximately 150 liters) of rice. This was expected to promote a shift from a barter economy to a currency economy. However, in reality, circulation was limited, and acceptance among the common people did not advance. Nevertheless, this attempt was an important step in ancient Japan's economic policy and laid the foundation for the subsequent Kōchō Jūnisen. Wadōkaichin was a symbol of national prestige and simultaneously demonstrated its ambitions and limitations. Considering the circumstances of the times, the Kōchō Jūnisen was more than mere coins; it was an entity reflecting the challenges of the era. Understanding why the Kōchō Jūnisen was necessary between 708 and 958 deepens the weight felt in each piece.

The minting of Kōchō Jūnisen evolved technologically over time. In the initial minting of Wadōkaichin, copper-based alloys were used, but as time progressed, copper shortages became severe. Especially by the mid-Nara period, alloys mixed with lead or zinc started to be used instead of copper. This was due to the depletion of copper mines and the impact of the influx of Chinese coins. At the Mint Bureau established near the Heijō Palace ruins in Nara City, skilled artisans continued to seek more efficient minting methods. They tried to enhance the coins' value by improving molds and applying more intricate designs. Under the Ritsuryō system, this minting process progressed as part of national economic policy, and the political intentions of each era were strongly reflected. Inflationary policies, such as setting the face value ten times that of the previous coins for each minting, were unique attempts of this era. However, whether such policies were sustainable in the long term is questionable. The traces of handiwork left on the construction of Kōchō Jūnisen provide crucial clues for determining authenticity and lineage in modern appraisal.

The minting of Kōchō Jūnisen theoretically should have permeated the currency economy throughout Japan. However, their actual circulation was limited, and bartering remained prevalent, especially in rural areas. From the late Nara period to the Heian period, even when observing major trade routes in Japan, there are few traces showing that these coins were actually used. In urban areas, there was a certain amount of circulation, but for rural commoners, the Kōchō Jūnisen held only 'value as tax.' Exchange rates were unstable, with the price of a koku of rice varying significantly by region, and the coin's value sometimes fluctuated abruptly. As a result, distrust in using coins grew among commoners. Furthermore, due to the influx of Chinese coins, the value of the Kōchō Jūnisen decreased relatively, and their circulation decreased. This highlighted the vulnerability of the monetary system, coinciding with the decline of the Ritsuryō state. The movement of Kōchō Jūnisen in the market was intimately tied to the lives and prices of the time, providing clues to understanding monetary history. How the Kōchō Jūnisen was received or shunned itself tells the economic reality of the times.

The Kengen Taihō was minted in 958, marking the end of Kōchō Jūnisen. With the collapse of the Ritsuryō system, the state’s ability to supply coins reached its limit. After Kengen Taihō, Japan's economy was supported by imported coins from China and privately minted coins. The impact of the monetary policies from this era extended to the currency system of the Edo period. In particular, the importance of state-supplied currency was re-evaluated in the details of the Keichō Koban of the Edo period. Even today, Kōchō Jūnisen is indispensable in discussing Japan's monetary history, with its rarity leading to high trade values among antique coin collectors. Especially late-period coins are extremely rare and hold very high value. These coins are valued not just as simple money but as important cultural heritage that tells the history and culture of Japan. Looking back from later generations, the influence left by Kōchō Jūnisen quietly persists in the history of subsequent coins and collecting. Considering how Kōchō Jūnisen is evaluated in the modern market leads to cultivating an eye for both history and market value.