The Canton System (1757–1842) served as a means for China to control trade with the west within its own country by focusing all trade on the southern port of Canton (now Guangzhou). Known in Chinese as the Yī kǒu tōng shāng (一口通商, "Single port commerce system") the policy arose in 1757 as a response to a perceived political and commercial threat from abroad on the part of successive Chinese emperors.
From the late seventeenth century onwards, Chinese merchants known as Hongs (háng, 行 ) managed all trade in the port. Operating from the Thirteen Factories located on the banks of the Pearl River outside Canton, in 1760, by order of the Qing Qianlong Emperor, they became officially sanctioned as a monopoly known as the Cohong. Thereafter Chinese merchants dealing with foreign trade (known as yanghang (洋行, literally "ocean traders") acted through the Cohong under the supervision of the Guangdong Customs Supervisor (Yuèhǎi guānbù jiàn dù, 粵海關部監督), informally known as the "Hoppo", and the Governor-general of Guangzhou and Guangxi.