Jiangsu was originally part of the Wu kingdom, and Wu is still the province's traditional name. Jiangsu received its present name, derived from Jiangning (Nanjing) and Suzhou (Soochow), in 1667, when it was formed from the old Jiangnan province. The gateway to central China, Jiangsu became the main scene of European commercial activity after the Treaty of Nanjing (1842). The capture of Jiangsu in 1937 was an important phase of Japan's effort to conquer all China (see Sino-Japanese War, Second). Liberated by the Chinese Nationalists in 1945, Jiangsu fell to the Communists in 1949. For a time Jiangsu was administered as two regional units, North and South Jiangsu, but in 1952 the province was reunited. Many archaeological sites have been excavated in Jiangsu since 1956. In 1984 the province was made a part of the Shanghai special economic zone, which has increased investment in and exports from port cities like Nantong.