Tsushima Province (対馬国; Tsushima-no kuni) was an old province of Japan (-19c) on the Tsushima Islands which occupied the area corresponding to modern-day Tsushima, Nagasaki. It was sometimes called Taishū (対州).

Political History

Since the establishment of the Ritsuryo system , Tsushima Province has been a strategic area that took a major role in the national defense against possible invasions from the continent and in trade with the Korean Peninsula. After Japan was defeated by the Tang at the Battle of Hakusukinoe in 663, Kaneda Castle was constructed on this island.

Tsushima Province had been controlled by the Tsushima-no-kuni-no-miyatsuko clan until the Heian Period. This clan was replaced by the Ahiru clan. The So clan rose into power around the middle 13th century and seized control of the whole island in the late 15th century. During the Edo period, Tsushima Province was dominated by the Tsushima Fuchu domain (Izuhara domain) of the So clan. It was put in charge of diplomacy and monopolized trade with the Joseon Dynasty of Korea.

As a result of the abolition of the Han system, the Tsushima Fuchu domain became Izuhara Prefecture in 1871. In the same year, Izuhara Prefecture was merged into Imari Prefecture, which was renamed Saga Prefecture in 1872. Tsushima was transferred to Nagasaki Prefecture in 1872.

Districts

Throughtout the history, Tsushima Province consisted of two districts:

• Kamiagata (上県)
• Shimoagata (下県)

The capital was put at Izuhara. In modern local municipality system, they became Kamiagata District and Shimoagata District respectively, and were merged into the city of Tsushima today.