CHINA, JAPAN, AND KOREA, 1840–1937 The Opium Wars of the 1840s and 1850s and the Boxer Rebellion of 1899–1901 changed the shape ofimperialism in Asia. These conflicts led to the establishment of special territorial enclaves and treaty ports within China, areas reserved for each imperial power. By the early twentieth century, Japan had taken advantage of China’s declining fortunes to gain control..