The illegal drug trade is a global black market dedicated to the cultivation, manufacture, distribution and sale of drugs that are subject to drug prohibition laws. Most jurisdictions prohibit trade, except under license, of many types of drugs through the use of drug prohibition laws.
A UN report has stated that "the global drug trade generated an estimated US$321.6 billion in 2003." With a world GDP of US$36 trillion in the same year, the illegal drug trade may be estimated as nearly 1% of total global trade. Consumption of illegal drugs is widespread globally.
Chinese edicts against opium smoking were made in 1729, 1796 and 1800. Addictive drugs were prohibited in the west in the late 19th and early 20th centuries.
In the early 19th century, an illegal drug trade in China emerged and as a result, by 1838 the number of Chinese opium addicts had grown to between four and twelve million. The Chinese government responded by enforcing a ban on the import of opium that led to the First Opium War (1839-1842) between the United Kingdom and Qing dynasty China. The United Kingdom won and forced China to allow British merchants to trade opium. Trading in opium was lucrative, and smoking opium had become common in the 19th century, so British merchants increased trade with the Chinese. The Second Opium War broke out in 1856, with the British joined this time by the French. After the two opium wars, the British Crown, via the treaties of Nanking and Tianjin, the Chinese government was obliged to pay large sums of money for opium they had seized and destroyed, which were referred to as "reparations".