Standard cash (zhiqian 制錢) were copper coins produced in imperial mints according to standards fixed by the government. The term was used during the Ming 明 (1368-1644) and Qing 清 (1644-1911) periods in order to discern full-valued coins from older ones (jiuqian 舊錢) from the Song period 宋 (960-1279) and private forgeries (siqian 私錢, sizhuqian 私鑄錢). The standard cash coin in China was round, with a square hole in the middle. There inner and outer rim was slightly elevated, and on one side, the reign motto was inscribed, on the other occasionally some additional information, but in general the rear side was blank. The shape of the inscribed characters was a hint to the provincial mint where the coin had been cast.
In 1361 the young Ming dynasty established the first imperial mint (baoyuanju 寶源局) in the capital Yingtian 應天 (today's Nanjing 南京, Jiangsu) where the new coins with the legend Dazhong tongbao 大中通寶 were cast, circulating side by side with older coins. From 1368 on (when the Ming dynasty ruled over the whole of China), in all provinces of the new empire, provincial mints (baoquanju 寶泉局) were established, where coins were produced with the legend Hongwu tongbao 洪武通寶. Private production of coins was strictly forbidden. The Hongwu tongbao coin was issued in the denominations ten cash (dang shi 當十, cash/qian 錢 is a weight unit), five cash (dang wu 當五), three, two, and one cash. The ten-cash coin was as heavy as one liang 兩 (c. 33-35 g), the five-cash coins half of it. After four years, it was decided to give up larger denominations, and to abolish the Dazhong tongbao. All coins were collected and recast to coins of one single denomination, the one-cash Hongwu tongbao, with a weight of 1 qian (c. 3.7 g).
The amount of copper coins produced by the Ming was higher than under the Yuan dynasty 元 (1279-1368) (which used paper bills, zhibi 紙幣, extensively), but never reached the output of the Song period. In 1393 there were 325 furnaces in the mints all over the provinces which had an annual performance of 189,000 strings of coins (with 1,000 coins per string). This was only 3 per cent of the annual mint production under the Northern Song 北宋 (960-1126). The raw material copper came from mines in the provinces of Jiangxi, Shaanxi and Shanxi. In Jiangxi alone, 115 furnaces were operating. In the other provinces, where copper ores were not found, the government ordered people to deliver copper objects to the mints for melting.
The emperors of the Yongle 永樂 (1403-1424), Xuande 宣德 (1426-1435) and Hongzhi 弘治 (1488-1505) reign-periods all had fresh coins cast, but there were other means of payment the government preferred, mainly bank notes (baochao 寶鈔), issued by private banks. Yet the high need for cash coins stimulated the production of forgeries that inundated the markets, often in such miserable quality that one real coin bought 300 fake ones. As a consequence, prices skyrocketed in many places. The situation was somewhat alleviated during the Jiajing reign-period 嘉靖 (1522-1566), when huge amounts of new cash coins were produced. In 1527 a large batch of Jiajing tongbao 嘉靖通寶 coins were produced, and in 1553 coins with the inscriptions of the nine earlier reign-periods, with an amount of 1 million ding 錠 per reign (1 ding = 5,000 cash), and a further lot of 10 million Jiajing tongbao coins. In the early seventeenth century the price of copper steeped, so that the government increased the amount of lead in the coin alloy. Coins from the Tianqi 天啟 (1621-1627) and Chongzhen 崇禎 (1628-1644) reign-periods were of very bad quality, thin and bristle, due to the low amount of copper. People therefore refrained from using copper cash, and preferred silver ingots instead.
The Manchus began casting coins (see money of the Qing period) even before the started the conquest of China. The earliest Manchu coin is the Tianming tongbao 天命通寶. In 1644 two mints were established in Bejiing, one under the jurisdiction of the Ministry of Revenue (hubu 戶部, the baoquanju 寶泉局 mint), and one under that of the Ministry of Works (gongbu 工部, the baoyuanju 寶源局). Each province was ordered to establish its own mint and cast copper cash. Money was produced in casting rounds (mao 卯), with predefined numbers of cash, copying the imperial standard with exact dimensions and proportions of metals in the alloy. On the obverse side of Qing cash, the reign motto was inscribed, like Qianlong tongbao 乾隆通寶, and on the reverse side the name of the mint in Manchu script (like ciowan boo ᠴᡳᡠᠸᠠᠨ ᠪᠣᡠ, i.e. quanbao; yuwan boo ᠶᡠᠸᠠᠨ ᠪᠣᡠ, i.e. yuanbao; fu boo ᡶᡠ ᠪᠣᡠ, i.e. Fujian; nan boo ᠨᠠᠨ ᠪᠣᡠ, i.e. Hunan; u boo ᡠ ᠪᠣᡠ, i.e. Wuhan, Hubei; su boo ᠰᡠ ᠪᠣᡠ, i.e. Suzhou, etc.). The standard alloy was 6 parts of copper and 4 parts of lead/zink, yet market conditions dictated the de-facto composition, and it was also officially changed over time: 3:2 in the beginning, then 6:4 during the Kangxi reign-period, 2:2 during the Yongzheng, and an addition of 2 per cent of tin during the Qianlong reign-period. The latter type of money was called "green cash" (qingqian 青錢). The actual weight of the standard coin also varied over time, between 1 qian and 1.4 qian. After 1733 it was fixed to 1.2 qian.
In Chinese the nominal unit of one coin was 1 wen 文, a unit still used today in colloquial Cantonese (mān), but written 蚊. The European traders called it "cash", which is also the weight unit qian. One thousand cash were stringed to one chuan 串 or guan 貫, and corresponded in the bimetallic currency system in Qing China to one liang 兩 of silver, by the Europeans called "tael". In fact, the exchange rate between one tael and cash coins varied from time to time and from place to place, depending on the value of both currencies. During the eighteenth century it was about 1 : 950, but rose in the first half of the nineteenth century to about 1 : 1,100, due to the decreasing quality of copper cash, and to some extent also to the drain of silver abroad. Cash coins were used for daily expenses, and silver taels for larger transactions. Tael/liang was also the common unit of account in merchant and government ledgers.
During the Xianfeng reign-period 咸豐 (1851-1861), it was decided to carry out a currency reform, and coins of larger denominations were produced.