Historical Background: Emergence of One of Japan's Oldest Coins
Mumon Gin-sen (無文銀銭) is considered one of the oldest coins in Japan, thought to have been used from the mid to late 7th century. During the Asuka period, a time when the Ritsuryō state was forming, this coin was utilized as a unique medium of exchange in Japan before the introduction of China's advanced monetary system. True to its name "mumon," the surface bears no inscriptions or patterns. Despite its simplicity, it suggests that silver held significant value in society at the time. Currently, it has been excavated from areas surrounding key regions of the Ritsuryō state, such as the remains of Sōfukuji Temple in Ōtsu City, Shiga Prefecture, and the Asukaike ruins in Asuka Village, Nara Prefecture. Discoveries from layers dating to the late 7th century at these sites suggest that Mumon Gin-sen may have existed simultaneously with or even earlier than the Wadōkaichin and Fuhonsen. It is an indispensable presence for understanding the dawn of Japan's monetary history. Broader knowledge of ancient coins can be deepened in the Introduction to Ancient Coins (Wadōkaichin, etc.).
Excavation of Asukaike Ruins and Impact on Japanese Monetary History
The large-scale excavation conducted in 1999 at the Asukaike ruins in Asuka Village, Nara Prefecture, significantly altered the historical evaluation of Mumon Gin-sen. This excavation uncovered Mumon Gin-sen from the same stratum as molds and defective pieces of Fuhonsen. This discovery strongly suggested the possibility that Mumon Gin-sen circulated as a precursor to or simultaneously with Fuhonsen. Until then, the starting point for the use of money in Japan was considered to be the Wadōkaichin of 708. However, the discovery at the Asukaike ruins revealed that a medium of exchange made of silver actually existed at an earlier stage in the 7th century. This fact has posed a reconsideration of the very definition of "oldest" in Japanese monetary history, delivering a great shock to the academic world. At the Sōfukuji remains as well, several Mumon Gin-sen have been unearthed, suggesting they were widely used in the core areas of the Ritsuryō state, such as Ōmi and Yamato.
Shape and Manufacturing Technique: Simple Silver Discs
Mumon Gin-sen are silver discs with diameters of approximately 28mm to 32mm and weights around 8g to 12g. As the name suggests, no inscriptions or patterns are engraved on their surfaces. This extremely simple shape lacks even the central hole seen in Chinese circular coins with square holes, indicating a unique Japanese monetary form of the time. It is presumed that the main manufacturing method was "casting," by melting silver at high temperatures and pouring it into molds to shape it. However, since the unearthed pieces display variations in size and weight, no rigorous unified standard, like those seen in modern times, is thought to have existed. This may suggest the limitations of manual manufacturing or differences in their uses. Metal composition analysis by X-ray fluorescence has confirmed that many specimens use relatively high-purity silver, revealing the advanced smelting techniques of the time. How such variations in standards affect the value of antique coins is explained in detail in Factors Determining the Value of Antique Coins.
Function as Weight Money: Coin or Material?
Whether Mumon Gin-sen functioned as "money" or merely as a measure of silver, that is, as "weight money," remains a subject of academic debate. The variation in weight is a primary basis supporting the weight money theory, where transaction was conducted by weighing. In ancient East Asia, weight money, which involved measuring uninscribed metal pieces for payments, was widely prevalent. In Japan as well, it is quite possible that imported or domestically produced silver was circulated similarly as a unit of measure. However, the relatively uniform disc shape suggests some degree of standardization consciousness and an intention to guarantee value. As it is not entirely disorderly silver lumps, some processing is evident. It has also been suggested that Mumon Gin-sen was in a transitional phase from pure weight money to "minted money" with fixed value. The classification system of currency can be further explored in Varieties and Classification Systems of Ancient Coins.
Relationship with Fuhonsen: Two Sources of Japanese Monetary History
Mumon Gin-sen and Fuhonsen are often compared and examined as two crucial sources in Japan’s ancient monetary history. Both existed around the same period in the late 7th century and are thought to have been distributed in related ways, given that they were excavated from the same stratum at the Asukaike ruins. However, Fuhonsen is inscribed with the characters "富本," whereas Mumon Gin-sen lacks inscriptions, marking a clear difference. This difference suggests the developmental stage of money. If Mumon Gin-sen had a strong character as weight money, Fuhonsen can be seen as a step towards "minted money" with more fixed value. Additionally, while Mumon Gin-sen is made of silver, Fuhonsen primarily consists of copper, implying that the relative values or uses of silver and copper at the time influenced the nature of each currency. For additional details on Fuhonsen, explore the Fuhonsen article for a deeper delve.
Market Trends and Rarity: Phantom Masterpiece
Due to the extremely limited existing number of Mumon Gin-sen, they rarely circulate in the market. Their rarity places them among the highest ranks of Japanese antique coins. The majority of confirmed finds have been recognized as important cultural properties of the country and are strictly stored in museums and research institutions, making it very rare for general collectors to see them. Should they ever appear on the market, prices of several million yen or more could be expected. However, due to an extremely limited number of actual transaction cases, presenting an accurate market price is challenging. Even at auctions specializing in antique coins, the handling of Mumon Gin-sen is extremely rare, with the appearance itself becoming a significant news event in the numismatic world. Such ultra-rare items are special cases where the general Antique Coin Market Cycle Reading Method tends not to apply.
Challenges in Authenticity Verification: Difficulty Due to Lack of Inscriptions
Authenticity verification of Mumon Gin-sen requires particularly advanced specialized knowledge and techniques among ancient coins. Since there are no inscriptions or patterns, typical verification methods such as script comparison cannot be used. Thus, verification mainly relies on multilateral scientific analysis and excavation records. Specifically, key considerations are: ① metal compositional analysis (confirming ratios of silver, copper, lead, etc., using XRF fluorescence analysis), ② presence or absence of excavation records (whether it is a legitimately excavated item), ③ nature and distribution of naturally formed patina on the surface, and ④ actual measured values of weight and diameter (genuine ones most often fall within a diameter of about 28-32mm and weight of about 8-12g). Most items claimed to be Mumon Gin-sen circulating on the market are highly likely to be later reproductions or forgeries. It is a principle of numismatic collecting to never touch unidentified items. Basic knowledge to discern authenticity can be learned in Complete Guide to Identifying Fakes and Altered Items.
Current State of Research and Observation Opportunities: Deepening the Mystery of Ancient Coins
In the research of Mumon Gin-sen, the Nara National Research Institute for Cultural Properties plays a central role, and its detailed records are included in the excavation report of the Asukaike ruins published in 2003. Archaeology and Japanese history scholars from the University of Tokyo and Kyoto University are also jointly continuing metallurgical analyses and investigations of excavation conditions, regularly publishing new findings. Currently, it has not been definitively concluded as "Japan's oldest currency," but there is unwavering recognition that it is decisive physical evidence showing the actual use of silver as a valuable medium of exchange in the 7th century Asuka period. Opportunities for the general public to view the actual Mumon Gin-sen are limited, but some excavated items may be displayed in special exhibitions at the Nara National Museum or the Asuka Historical Museum. Through these opportunities, one can experience the romance of ancient history.
Value of Ancient Silver and East Asian Trade: International Silver Circulation
In 7th-century Japan, where Mumon Gin-sen was used, silver held a special meaning beyond mere metal. In the then East Asian world, silver functioned as a broad value standard, and records show that it was actively used as gifts, tribute, and important trade goods among Japan, Baekje, Silla, and Tang. Multiple descriptions of silver appear in the Nihon Shoki, indicating that silver played a crucial role in court gift exchanges and foreign negotiations. Mumon Gin-sen can be positioned as a product born from such an East Asian scale silver distribution network. This eloquently testifies to the fact that Japan in the Asuka and Nara periods was not an isolated island nation, but actively participated as a member of an international economic sphere. This small silver disc quietly bears witness to the international status and economic activity of ancient Japan.