Ryō

A Ryō (^?) was a gold currency unit in pre-Meiji Japan Shakkanhō system. It was eventually replaced with a system based on the yen.

The ryō was originally a unit of weight from China, the tael. It came into use in Japan during the Kamakura period. By the Azuchi-Momoyama period it had become nearly uniform throughout Japan, about 4.4 monme as a unit of weight (about the same as 16.5 grams).

During the Sengoku period, various local daimyo began to mint their own money. One of the best known and most prestigious of these private coins was the koshukin issued by the warlord Takeda Shingen, who had substantial gold deposits within his territories. The value of the koshukin was based on its weight, with one koshukin equal to one ryō of gold, and thus stamped with its weight (approximately 15 grams). During the Tenshō period (1573-1592), one ryō was equal to four koku of rice, or 1000 brass coins.

The Tokugawa shogunate attempted to create a central currency, based on gold, silver and copper units all exchangeable at fixed rates. Oblong gold coins, called koban, were minted with one koban containing about one ryō of gold, so that koban carried a face value of one ryō. The official rate was set in 1609 at one ryō equal to 50 monme (approx 187 grams) of silver, or 4000 brass coins. However, in reality the relative values between gold, silver and brass currencies fluctuated on an almost daily basis throughout the Edo period.

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