Under the terms of the Treaty of Nanking, the five treaty ports including Shanghai were opened to foreign merchants, overturning the monopoly then held by the southern port of Canton (Guangzhou) under the Canton System.
Menurut syarat-syarat Perjanjian Nanjing, lima pelabuhan perjanjian termasuk Shanghai dibuka bagi para pedagang asing, menjungkalkan monopoli yang saat itu dimiliki oleh pelabuhan selatan di Kanton (Guangzhou) menurut Sistem Kanton.