Following the Second Opium War, representatives of the Qing dynasty signed the Treaty of Tientsin with Great Britain, one of several such treaties concluded that June with Western powers. The agreement opened ten more Chinese ports to foreign trade, legalized the opium trade, and permitted foreign diplomats to reside in Beijing, further eroding Qing sovereignty over its own borders and commerce.
By 1858, the Qing dynasty had already lost the First Opium War and ceded Hong Kong. The Second Opium War, triggered by the Chinese seizure of the ship Arrow and the murder of a French missionary, brought British and French gunboats up the Peiho River to the gates of Tianjin (then romanized as Tientsin), where imperial commissioners had little choice but to negotiate under the threat of an advance on Beijing itself.
The treaty's terms read like a checklist of humiliations later Chinese historians would call the 'unequal treaties': ten new treaty ports, freedom of movement for Christian missionaries throughout the interior, legal protection for the opium trade that had caused the war in the first place, and the right of foreign ministers to reside permanently in the capital, a demand the Qing court found particularly galling since it implied equality between the emperor and foreign sovereigns.
The emperor's officials had no real intention of honoring all its terms, and disputes over ratification led to renewed fighting in 1859 and 1860, culminating in the burning of the Summer Palace. The Tientsin treaties of 1858 mark a key step in China's 19th-century 'century of humiliation,' a period that still shapes Chinese nationalist politics and foreign policy rhetoric today.