Click to download the information "Treaty of Nanjing" How many taels of silver are 21 million silver dollars equal to? The 21 million yuan refers to the Spanish silver dollar, which is roughly equivalent to 14.7 million taels of silver. The Sino-British "Nanjing Treaty" stipulated that "China's compensation was 21 million silver dollars", and later China's compensation stipulated in Sino-foreign treaties was "a certain amount of taels of silver." Why did the names and units of calculations change? It turns out that this is closely related to the different states of China’s foreign trade before and after the First Opium War. Before the Opium War, China was in a leading position in Sino-foreign (mainly Sino-British) trade and obtained large amounts of trade profits from foreign countries every year. At that time, Britain prevented the outflow of currency and banned the export and circulation of its own silver coins. Therefore, the foreign trade profits earned by China were not pounds, but Spanish silver dollars obtained by British merchants from world trade. This silver dollar is native to Mexico. Mexico was the world's largest silver producer at that time. It began to mint silver coins during the Spanish colonial period. Its coins have a portrait of the King of Spain on the surface. It has the advantages of uniform color, neat specifications, and easy calculation and portability. It is widely circulated among the colonies of the world. British merchants also use a large number of this silver dollar in normal trade with China. Since China is in a leading position in Sino-foreign trade, a large amount of this silver dollar has flowed into the Chinese market, especially in Guangdong. The Treaty of Nanjing signed between China and Britain stipulated that China should compensate Britain 21 million silver dollars, which refers to this kind of Spanish silver dollar. This actually reflects the historical phenomenon that although China was closed to the outside world at the time, it was not without Sino-foreign trade, and China obtained a large amount of foreign exchange from it. So why did foreign reparations after the Treaty of Nanjing change to silver taels as the payment unit? Because after the Opium War, China gradually became a source of raw materials and a commodity market for Western powers, losing its advantageous position in Sino-foreign trade. China's silver drained out in large quantities, and China had to use traditional Chinese silver ingots to pay huge amounts of compensation.