Tsushima (対馬, Korean Daema) was a province of Japan until the abolition of provinces and establishment of prefectures. Tsushima is an island belonging to Japan, situated about midway between Korea and the island of Kyushu, so that the island was used as a port of call in former times by vessels plying between Japan and Korea. The nearest port on the Korean coast at Busan is 49.5 km away and the nearest Japanese port of Fukuoka is 147 km away. It has an area of 262 km². It is divided at the waist by a deep sound (Aso-wan), and the southern section has two hills, Yatachi-yama and Shira-dake, 2130 ft. and 1680 ft. high respectively, while the northern section has Ibeshi-yama and Mi-take, whose heights are 1128 ft. and 1598 ft. The chief town is Izuhara.
The inhabitants of the islands were apparently Japanese, speaking Japanese dialects. Since ancient times, the islands have belonged to Japan as her province, though some of the earliest colonizers of the island are believed to be former subjects of the fallen Korean kingdom Baekje during the late 7th century. The island remained sparsely populated and served as a key trading port, being influenced by both Korea and Japan. In the 13th century, the Mongols who established dominance over Goryeo in Korea, sent their armada to Tsushima, where they wrought great destruction to the island in 1274 and 1281. However, the Mongols were halted from further aggression into Japan.
After the withdrawal of Mongol influence from Goryeo in Korea, the island became a haven for pirates, who took advantage of the constant trade between Korea and Japan. In 1419, King Sejong of Joseon in Korea ordered his trusted general Lee Jong Mu to clear the island of these pirates. At this time, Tsushima came under the sphere of influence of Joseon.
In the late 16th century, as Toyotomi Hideyoshi united the various feudal barons under his control and looked to unite all factions with a common cause, he looked to invade Joseon. In preparation for this war, Tsushima became the main naval base for this invasion. From this point, Japan developed a strong foothold in Tsushima.
After peace was re-established between the two nations--after Japan's invasion attempts failed due to Ming China's involvement in support of Joseon--the island once again became a port for merchants to dock their ships. Both Joseon and Tokugawa shogunate sent their trading representatives to Tsushima to govern trade. Japanese rule was slowly established as Joseon had no intention of colonizing the island following its policy of leaving islands uninhabited. During the late 19th century, the Meiji government of Japan officially incorporated the island into its country.
During the Russo-Japanese War in 1905, the famous Russian Baltic fleet under Admiral Rozhdestvensky, which made a nearly year-long trip to East Asia from the Baltic coast, was crushed by the Japanese under Admiral Togo Heihachiro at the Battle of Tsushima.
After World War II, there arose a movement in South Korea to claim Tsushima, touting its historical relations to the various kingdoms of Korea. This was made most evident when President Syngman Rhee, in a beginning-of-the-year press conference in 1949, formally requested that Japan return the island to Korean rule. However, this claim was never seriously considered by the military government of General Douglas MacArthur. With the outbreak of Korean War the next year and the economic struggles that South Korea faced in the following decade, talk of any territorial dispute disappeared.
Tsushima is the closest Japanese territory to Korea.