Ryo (A Former Japanese Weight Unit, And Also A Former Japanese And Chinese Currency Unit) (両)
Ryo served as a weight unit in the traditional East Asian system of weights and measures, and also served as a currency unit in Japan and in China; in Japan, the unit of gold coins in the early modern ages, and in China, the unit of hyoryo ginka (silver coin used as currency by weight).
As a weight unit, ryo had a heavier scale than monme (former Japanese weight unit) and a lighter scale than kan and kin (kan and kin were both former Japanese weight units), and in Japan, 1 ryo, 10 monme, 0.01 kan, and a 16th kin were equalized. Under the Taiho Code promulgated in the Nara period, the weight of 1 ryo was set around 41to 42 grams, following the standard of the Sui Dynasty (or the early Tang Dynasty) China, and when the weight of 1 ryo was reduced by around 11 percents into 37.3 grams in Tang Dynasty, Japan followed China again and took almost the same standard. After the Meiji period, ryo as the weight unit has rarely been used in Japan. In today's China, 1 ryo (liang in Chinese) is set at 50 grams.
As the currency unit of gold coins, ryo was established by Koshu-kin (the gold coin minted in Koshu Province), which Shingen TAKEDA ordered to coin, and handed down to the Edo bakufu (Japanese feudal government headed by a shogun); 1 ryo was equalized with 4 bu, or 16 shu (bu and shu were former Japanese currency unit). 1 ryo had currency value as 1 koban (former Japanese gold coin of oval shape) which 1 ryo was equivalent to 2 nibu-kin (former Japanese gold coin of 2 bu), 4 ichibu-kin (former Japanese gold coin of 1 bu) or ichibu-gin (former Japanese silver coin of 1 bu), 8 nishu-kin (former Japanese gold coin of 2 shu) or Nanryo nishu-gin (former Japanese silver coin of 2 shu), 16 isshu-kin (former Japanese gold coin of 1 shu) or isshu-gin (former Japanese silver coin of 1 shu) accordingly. In the Meiji period, yen was introduced as the currency unit, however, '1 yen was equivalent to 1 ryo' in changeover phase, so 'yen' was called 'ryo' for a while. And from around the Bunsei era (1818 to 1830) in the Edo period, it is said some called 'yen' as 'ryo' habitually.
History
Ryo as the weight unit
Ryo as the weight unit originated in ancient China.
"Book of Han, Treatise on rhythm and the calendar" in Han Dynasty says as follows:
The units of weight are shu (in pinyin, 'zhu'), ryo, kin (in pinyin, 'jin'), kin (in pinyin, 'jun'), and koku (in pinyin, 'dan').'
By diffusing the units, the weight of things can be known.'
Originally, the name of shu came from the weight of the proso millet grains that are fully put into Kosho pipe, a kind of flute.'
The volume of kosho pipe (= 1 'yaku') is the same as the volume of 1200 proso millet grains, whose weight is 12 shu.'
And twice the 12 shu is set equal to 1 ryo.'
In short, the volume of an kosho pipe (= 1 yaku) is the same as the volume of 1200 proso millet grains, and the weight of the 1200 grains was set equal to 12 shu (銖; 朱 in abbreviation), and twice the 12 shu, or 24 shu, was set equal to 1 ryo.
Incidentally, the Chinese character of '両' (reads as ryo) has the second meaning of 'two.'
Here, 1 ryo was roughly equal to 3 sen (also called monme in Japan) and 8 bu. Under the Tang Dynasty, the system of larger ryo, which was three times larger than ryo, was established that larger ryo weighed 11 sen and 4 bu, which was three times as much as 3 sen and 8 bu. And later in Tang Dynasty, the weight standard of 'kin' and 'ryo' was reduced and Kaigen Tsuho ('Kai Yuan Tong Bao' in pinyin, a coin of the Tang Dynasty China) was minted at the weight of a 10th of 1 ryo which was equivalent to 10 sen (or 10 monme). Both 'ryo,' smaller ryo and larger ryo, were introduced into Japan.
When we weigh 1 ryo with chia-liang standard measure in "Book of Han, Treatise on rhythm and the calendar," actual measured value was 14.167 grams which equivalent to 1 'smaller ryo.'
And when we weigh 1 ryo with the standard of Sui Dynasty China in "History of Chinese Weights and Measures," written by Wu Chengluo, the value was 41.762 grams, which was about three times as much as the previously-mentioned weight with chia-liang, and with the standard of the Tang Dynasty, 1 ryo weighed at 37.301 grams which equivalent to 1 'larger ryo.'
This Tang Dynasty's 'ryo' was introduced into Japan to be used until the early Edo period, then in 1661, the Japanese weight units were standardized. And thereafter, Shirobei GOTO family was only allowed to produce fundo (counterweight) used at an exchange house, and the production and use of other kinds of fundo was prohibited strictly for the prevention of illegal exchange.
The basic weight unit of the fundo was 'ryo.'
However, to avoid mixing up 'ryo' of the currency unit for koban, 'monme' and 'kan' were used as the currency unit for hyoryo ginka. In other words, when chogin (the silver coin used as the currency by weight) was balanced with 4 ryo of fundo, the chogin's currency value was equivalent to 40 monme of silver. By an actual measured value of the fundo, 1 ryo in the Edo period was around 37.46 to 37.47 grams.
Meanwhile in China, 1 ryo (larger ryo) with actual measured value of hyoryo ginka was equivalent to 1 ryo of silver (ginryo). When the Treaty of Amity and Commerce between the United States and Japan was concluded in 1858, the fact that about 8.6-gram ichibu-gin was coincidentally equivalent to around one fourth ryo in weight, which was worth of one fourth ryo of silver at face value, provided Townsend Harris with the excuse of insisting unfavorable exchange rate for Japan that three ichibu-gin coins changed one-dollar silver coin which was about three fourth weight of Chinese one ryo of silver and led koban flow out.
When the New Currency Act was promulgated in June 1871, the weight of 1 sen (monme) was set at 3.756574 grams at first, and then in October of the same year, it was reset at 3.756521 grams, so the weight of 1 ryo became 37.56521 grams.
Afterward, the metric system was introduced into Japan for convenience in conversion among units, and in 1891, the Weights and Measures Act set 1 kan at 3.75 kilograms, so 1 ryo became equal to 37.5 grams. From the Meiji period in Japan, however, only 'kan' and 'monme' became used in the traditional Japanese system of weights and measures, and 'ryo' became rarely used because it was neither mentioned in the New Currency Act nor in the Weights and Measures Act. The Weights and Measures Act was abolished in 1951, and later, the Measurement Act standardized Japanese measurement units into the metric system, when ryo was ended in its official use.
As the weight standards of drugs, 1 ryo was commonly equalized with 4 monme (that is, 1 smaller ryo), but occasionally, 1 ryo was equalized with 4 monme and 4 bu, or 5 monme for some drugs.
"Shugaisho" (an ancient encyclopedia), which is said to have been compiled around 1300, has an article that it is related to daho (a system of weight units, seen for the load carried by a horse). And the article says that ome (the weight standard that set 200 monme equal to 1 kin) was used for weighing powdered calcium carbonate, a lump of pewter, copper, and iron, floss silk red (絲綿紅), and sappan wood red, and it also says that kome (the weight standard smaller than the usual one) was used for weighing gold, silver, crystal, Radix Aristolochiae (a kind of herbal medicine), lapis lazuli, malachite, and pottery. And the article also says that there existed a weight units' system peculiar to those things, in which '6 shu were equivalent to 1 bu, 4 bu to 1 ryo, 12 ryo to 1 ton, 16 ryo to 1 small kin, and 3 kin to 1 large kin.
The book says that the existence of the previously-mentioned system was just a popular belief, while just the same system is said to have existed in daho of the Tang Dynasty China. Here, 1 bu is not a 10th of 1 sen (monme) at all. ryo' and 'bu,' which were incorporated into Koshu-kin and the currency system of the Edo period, were highly likely to have been based on the previously-mentioned system, and the weight units' system of drugs was modeled after that of gold and silver.
In China, the government of the Nationalist Party promulgated the Weights and Measures Act in 1929, and in the provision, '1 tan (dan in pinyin) was equivalent to 100 kin, 1 kin to 16 ryo, 1 ryo to 10 sen, and 1 sen to 10 bu,' and the weight of 1 ryo was set at 37.301 grams, modeled after the standard in the Tang Dynasty China. Today, 10 times the weight of 1 sen (or 1 monme in Japan) is equivalent to 1 ryo (or 1 liang in pinyin), and 10 times the weight of 1 ryo is equivalent to 1 kin (or 1 jin in pinyin). But it was only in the age of People's Republic of China that 10 ryo was equalized with 1 kin, and until then, 16 ryo had been equalized with 1 kin. 1 liang is set equal to 50 grams (refer to the article of "Chinese Traditional System of Measurement"). But in Hong Kong, which was under the British rule as of 1929, the weight of 1 kin and 16 ryo are equally 600 grams even today, in other words, the weight of 1 ryo is set at 37.5 grams.
Ryo as a currency unit
Originally, 1 ryo of gold meant 1 ryo (or 1 small ryo under the Taiho Code, 10 monme under the Engi Code and thereafter) of gold dust. But as times went by, the weight of ryo became far apart from the value of ryo; in Kamakura period 1 ryo of gold was equivalent to 5 monme and that of silver 4.3, then in the late Kamakura period, 1 ryo of gold turned to be 4.8 monme from 4.5. In 1484, Muromachi bakufu officially established 1 ryo of Kyome (the weight standard used in and around Kyoto, applied to the gold currency) was equivalent to 4.5 monme (about 16.8 grams) then in Azuchi Momoyama period (or Genki and Tensho eras [1570 to 1592]), 1 ryo of Kyome was changed to 4 monme and 4 bu (about 16.4 grams) and the weight standards other than Kyome were called Inakame. Koshu-kin was produced based on 1 ryo of Inakame, that is, 4 monme (about 14.9 grams), and the currency units became the basis for koban's face value, 1 ryo.
The currency units of Koshu-kin had the quaternary numeral system, in which '1 ryo, 4 bu, 16 shu, and 64 itome were equalized.'
This system was succeeded to Tokugawa shogunate which was basis for the currency in the Edo period.
10 ryo (or 44 monme) of gold was called 1 tsutsumi, or 1 mai, which later became the weight standard of oban (former Japanese large gold coin of oval shape), and similarly, 10 ryo (or 43 monme) of silver was called 1 tsutsumi or 1 mai as well, which later became the weight standard of chogin.
The weight of Keicho Koban (the Japanese gold coin of oval shape minted in the Keicho era [1596 to 1615]) was determined based on 1 ryo of Kyome by taking complicated factors into consideration. After that, however, reminted koban became inferior both in percentage of gold and in weight, then ryo as the weight unit became far apart from ryo as the currency unit.
The Japanese word 'ryogae' (exchange) came from changing (in Japanese, 'kae' or 'gae') 1 ryo of koban at an exchange house into various other coins, such as hyoryo ginka and the copper coin. Another theory says it came from what is called nanryogae that is the exchange of silver by cupellation with chogin at gin-za (an organization in charge of casting and appraising of silver during the Edo period).
In the Tensho era (1573 to 1592), 1 ryo was almost equal to the following things in value, that is, 4 koku of rice, 1 kanmon (former Japanese currency unit) of Eiraku Tsuho (Yong Le Tong Bao in pinyin, a copper coin minted in Ming dynasty China), and 4 kanmon of bad copper coins.
In the Edo period, the exchange rate among koban, chogin, and copper coin fluctuated day by day. Meanwhile, Edo bakufu set the mint par of exchange, proclaiming in 1609 that 1 ryo of gold was equalized to 50 monme of silver (about 187 grams), or to 4 kanmon (or 4000 mon) of copper, then later in 1700, proclaimed again that 1 ryo of gold became 60 monme of silver (about 225 grams), or 4 kanmon of copper. But such interventions of the bakufu were implemented only when the exchange market overheated, and usually the exchange business was left into the hands of the market.
Although some fluctuations were seen under the influence of reminting, famine, and others, the price of 1 koku rice (nearly equal to the amount consumed by a person per year) was around 1 ryo from the Genroku era (1688 to 1704) until just before the last days of the Tokugawa shogunate when the Japanese society became unstable.
There exist various theories about how much currency value 1 ryo has today. Relatively, the value in Keicho era was different in more than one digit from that in the end of Edo period by its sharp depreciation, moreover, since the life style was completely different from that of today, it varied greatly whether it was the standard of wage or commodity price which differed from items. According to the web site of Currency Museum at Bank of Japan's Institute for Monetary and Economic Studies, with the standards in Genbun era (1736 to 1741), 1 ryo is equivalent to about 40,000 yen in rice price, to 300,000 to 400,000 yen in wage, and to 120,000 to 130,000 yen in buckwheat noodles price.
Meanwhile, in China, a mass of silver, called silver sycee, served as the currency, whose value depended on its weight, and its currency unit was ryo (also known as ginryo or tael). The shape of the silver sycee varied depending on the age and area it was minted as it was issued by private sector. It was only in 1933 that the use of this currency was ended completely (the abandonment of the old 'ryo' and its replacement with the 'yuan').