Chŏngjin (tshʌŋ.dʑin; ) is the capital of North Korea's North Hamgyong Province (함경북도) and the country's third largest city. It is sometimes called The City of Iron.
According to archaeological findings near the lower areas of the Tumen river, evidence of human living traces back to the paleolithic period.
According to the Records of the Grand Historian, the region was where the tribe kingdoms of Buyeo, Mohe, Okjeo, Yilou, Yemaek and Sushen existed. The region later was the territory of Goguryeo. After the fall of Goguryeo in 668, the region was ruled by the Tang dynasty. During the reign of Balhae, the region was under the subdivision donggyeongyongwonbu. The region was under the rule of the Jin dynasty and Yuan dynasty after the fall of Balhae by the Khitans.
Chongjin was a small fishing village prior to the Japanese annexation of Korea; its date of establishment is unknown. The Chinese characters for its name mean 'clear river crossing'. During the Russo-Japanese War of 1904–1905, Japanese forces landed at Chongjin and established a supply base due to its proximity to the front lines in Manchuria. The Japanese remained after the end of the war, and in 1908, declared the city an open trading port both for the transport of Korean resources and as a stopping point for resources from China. The city was known during this period as “Seishin”, after the Japanese pronunciation of the Chinese characters for its name. The Imperial Japanese Army’s 19th Division was headquartered in Ranam from 1918, where the Japanese built a new planned city based on a rectangular street grid. In 1930, Nippon Steel built a large steel mill, the Seishin Iron and Steel Works, in the town. Ranam was annexed to Chongjin in 1940, which was elevated to city status. The city was overrun after a brief resistance by the Soviet Union on 13 August 1945, only two days before the end of World War II. Under the rule of North Korea, Chongjin remained an important military and industrial centre. It was directly administered by the central government from 1960–1967 and from 1977–1988.