U+8CAB CJK Unified Ideo­graph-​8CAB

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A string of cash coins (Traditional Chinese: 貫, 索, 緡, 繦, 鏹, 吊, 串, 弔, 錢貫, 貫錢, 貫文, 吊文, or 串文; French: Ligature de sapèques) refers to a historical Chinese, Japanese, Korean, Ryukyuan, and Vietnamese currency unit that was used as a superunit of the Chinese cash, Japanese mon, Korean mun, Ryukyuan mon, and Vietnamese văn currencies. The square hole in the middle of cash coins served to allow for them to be strung together in strings. The term would later also be used on banknotes and served there as a superunit of wén (文).

Prior to the Song dynasty strings of cash coins were called guàn (貫), suǒ (索), or mín (緡), while during the Ming and Qing dynasties they were called chuàn (串) or diào (吊). In Japan and Vietnam the term 貫 would continue to be used until the abolition of cash coins in those respective countries.

During the Qing dynasty a string of 1000 cash coins valued at 1 tael of silver, although variants of regional standards as low as 500 cash coins per string also existed. A total of 1000 coins strung together were referred to as a chuàn (串) or diào (吊) and were accepted by traders and merchants per string because counting the individual coins would cost too much time. Because the strings were often accepted without being checked for damaged coins and coins of inferior quality and copper alloys, these strings would eventually be accepted based on their nominal value rather than their weight; this system is comparable to that of a fiat currency. Because the counting and stringing together of cash coins was such a time-consuming task, people known as qiánpù (錢鋪) would string cash coins together in strings of 100 coins, of which ten would form a single chuàn. The qiánpù would receive payment for their services in the form of taking a few cash coins from every string they composed. Because of this, a chuàn was more likely to consist of 990 coins rather than 1000 coins, and because the profession of qiánpù had become a universally accepted practice, these chuàns were often still nominally valued at 1000 cash coins. The number of coins in a single string was locally determined, as in one district a string could consist of 980 cash coins, while in another district this could only be 965 cash coins. These numbers were based on the local salaries of the qiánpù. During the Qing dynasty the qiánpù would often search for older and rarer coins to sell these to coin collectors at a higher price.

The number of cash coins which had to be strung together to form a string differed due to region, time period, or by the materials used in the manufacture thereof. For example, under the reign of the Tự Đức Emperor of the Nguyễn dynasty, one string of cash coins included 600 zinc coins, while during the later days of the French colonial period, a string of cash coins was 500 copper alloy coins. In Vietnam a string of cash coins had the nominal value of 1 Mexican peso or 1 French Indochinese piastre. During the late 19th century in Qing China, some currency systems were named after how many cash coins made up a string, such as the Jingqian (京錢, 'metropolitan cash') or Zhongqian (中錢), which was an exchange rate that was used in the capital city of Beijing. The Jingqian system allowed a nominal debt of 2 wén (文) which could be paid out using only one physical cash coin instead of two. In this system a string of Beijing cash coins (吊) required only 500 cash coins as opposed to the majority of China, which used 1000 cash coins for a string (串). Meanwhile, in the Dongqian (東錢, 'Eastern cash') system, an exchange rate used for cash coins in the Fengtian province, only 160 cash coins were needed to make up a string. During the Qing dynasty period, the term chuàn was used to designate long strings while the term diào was used to design short strings.

Although the term appeared frequently on banknotes, the only cash coin to have ever had the currency unit "String of cash coins" as a part of its inscription was the Nguyễn dynasty-era Tự Đức Bảo Sao (嗣德寶鈔) 1 quán cash coin (準當一貫, chuẩn đang nhất quán), which was worth 600 văn (or 60 mạch).