Starting with the rise of nationalism and anti-imperialism in the 1920s, the Kuomintang and Chinese Communist Party used these concepts to characterize the Chinese experience in losses of sovereignty between roughly 1839 to 1949. The term "unequal treaty" became associated with the concept of China's "Century of Humiliation", especially the forced opening of the treaty ports, the imposition of European extraterritoriality on foreigners living in China, and loss of tariff autonomy.
In China, the term "unequal treaty" first came into use in the early 1920s. Dong Wang, a professor of contemporary and modern Chinese history, noted that "while the phrase has long been widely used, it nevertheless lacks a clear and unambiguous meaning" and that there is "no agreement about the actual number of treaties signed between China and foreign countries that should be counted as 'unequal'." Historian Immanuel Hsu explained that the Chinese viewed the treaties they signed with Western powers as unequal "because they were not negotiated by nations treating each other as equals but were imposed on China after a war, and because they encroached upon China's sovereign rights ... which reduced her to semicolonial status". In response, historian Elizabeth Cobbs wrote, "Ironically, however, the treaties also resulted partly from China's initial reluctance to consider any treaties whatsoever, since it viewed all other nations as inferior. It did not wish to be equal."
In many cases, China was effectively forced to pay large amounts of reparations, open up ports for trade, cede or lease territories (such as Outer Manchuria and Outer Northwest China to Russian Empire, Hong Kong to Great Britain and Zhanjiang to France), and make various other concessions of sovereignty to foreign "spheres of influence", following military defeats. The earliest treaty later referred to as "unequal" was the 1841 Convention of Chuenpi negotiations during the First Opium War. China and Great Britain signed the first unequal treaties under the Treaty of Nanjing in 1842. Following Qing China's defeat, treaties with Britain opened up five ports to foreign trade, while also allowing foreign missionaries, at least in theory, to reside within China. In addition, foreign residents in the port cities were afforded trials by their own consular authorities rather than the Chinese legal system, a concept termed extraterritoriality. Under the treaties, the UK and the US established the British Supreme Court for China and Japan and United States Court for China in Shanghai.
After World War I, patriotic consciousness in China focused on the treaties, which now became widely known as "unequal treaties". The Nationalist Party and the Communist Party competed to convince the public that their approach would be more effective. Germany was forced to terminate its rights, the Soviet Union surrendered them, and the United States organized the Washington Conference to negotiate them. After Chiang Kai-shek declared a new national government in 1927, the western powers quickly offered diplomatic recognition, arousing anxiety in Japan. The new government declared to the Great Powers that China had been exploited for decades under unequal treaties, and that the time for such treaties was over, demanding they renegotiate all of them on equal terms. In the face of Japanese expansion in China, however, ending the system was postponed.
Most of China's unequal treaties were abrogated during the Second Sino-Japanese War, which started in 1937 and merged into the larger context of World War II. The United States Congress ended American extraterritoriality in December 1943. Significant examples of unequal treaties with China did outlast World War II: unequal treaties regarding Hong Kong remained in place until Hong Kong's 1997 handover, and in 1969, to improve Sino-Russian relations, China reconfirmed the 1859 Treaty of Aigun.