In 1842, the Treaty of Nankin ended the First Opium War, but it also forced China to open several "treaty ports" to European trade. One of these was Shanghai, a small fishing village near the mouth of the Yangtsé River. European merchants, including British, French, American, and later Japanese colonists, settled in areas known as concessions, which were autonomous zones within the city. The arrival of these foreigners, along with refugees from the Taiping Rebellion and later Jewish refugees from World War II, helped Shanghai become a major center of commerce, finance, and industry. Though Westerners remained a minority—about 150,000 in the early 1940s—their influence was significant, especially on the Bund, a historic district along the Huangpu River. Near the Custom House, which featured a clock reminiscent of Big Ben, a row of gleaming, towering buildings rose. Among them was the Bank of China, constructed in 1937. Originally planned for eighteen floors, the design was reduced after protests from Sir Victor Sassoon, the architect of the Sassoon House, later renamed the Peace Hotel. Foreign residents brought nightclubs to Shanghai, where people could drink and dance. After World War I, many such venues opened, welcoming musicians from Europe and the United States. Shanghai locals quickly embraced new dances like jazz, foxtrot, and charleston, along with the alcohol that accompanied them. Men who arrived at clubs without partners—most of them—were assisted by "taxi-dancers" hired for the purpose. After each dance, patrons handed a ticket to the dancer, who then exchanged it for money. In 1923, Suzanne Tsang, daughter of Shanghai's reconstruction commissioner, caused a stir by attending a ball at the Carlton Café, challenging traditional norms. Her actions were soon imitated by other women seeking social entertainment. An American journalist wrote in 1935 that "at first, young Chinese women timidly went to the balls. Now, they move freely through the city, smoke, drink, and drive their own cars." Wealthy women in Shanghai rapidly adopted Western lifestyles. In photographs from the time, some women exposed their feet, symbolizing a break from the traditional practice of foot binding. Others began to wear short hair, challenging Confucian ideals of filial piety. The qipao, a tight-fitting dress, became popular in the 1920s, ranging from conservative styles to bold designs with long slits, as seen in the portrait of Ruan Lingyu, a famous actress of the era. In the 19th century, European banks in Shanghai profited from the opium trade, which the British had forced China to legalize through the Opium Wars. Tons of opium arrived in Shanghai's port and were distributed widely, with the drug known as "black rice" becoming common. A travel guide from the late 19th century described both the dangers and the allure of this situation: "The poison of opium has long circulated in China, from scholars to porters; almost no one remains untouched," it warned, while noting that "the opium dens of Shanghai are the best under the sky." In 1918, the city banned the opium trade and its derivatives, like morphine and heroin. However, the local Green Gang, led by Du Yuesheng, known as the "opium king," continued operating in the French-controlled areas. Opium use deepened economic and social divides, especially under Japanese occupation, where the trade boomed until Japan's defeat in 1945 and the establishment of the People's Republic of China in 1949, followed by anti-drug campaigns in the decades that followed. Shanghai's economic growth was accompanied by significant inequality and rising social and political tensions. On May 30, 1925, British police opened fire on Chinese protesters, sparking a large workers' and anti-imperialist movement. At the time, two political forces were gaining influence: the Kuomintang, a nationalist right-wing group, and the Chinese Communist Party, founded in Shanghai in 1921. Tensions peaked in 1927 after the Kuomintang army defeated Sun Chuanfang, a warlord who controlled Shanghai, and took over the city. Fearing attacks on the International Settlement and the French concession, the British, French, Americans, and Japanese sent military reinforcements. Instead of targeting Westerners, Kuomintang leader Chiang Kai-shek, with the help of the Green Gang, launched a brutal campaign against communists and their supporters. Thousands were killed in what became a turning point in the Chinese civil war.