Sado – an island in the eastern part of the Sea of Japan. Owned by Niigata Prefecture, Japan. It is the eighth largest Japanese island. The administrative center of the island is the eponymous city of Sado, which occupies a total area of the island.
Sado Island since ancient times served as a place of exile for political prisoners. In the VIII century, a separate province of Sado was formed here. Since 1185 the province was granted Honma Yoshihisa, whose house continued to rule the island until the XVI century. However, the subsequent division into two new branches Hamoti-Honma and Honma Kavaharada-led to civil war. The conflict between them has provoked Uesugi Kenshin, Echigo daimyo. By keeping the one, then the other members of Honma he achieved easing of their military forces. End of rule Honma put an open invasion of the samurai Uesugi, led by Uesugi Kagekatsu, in 1589
In the XVI century in Sado were discovered gold deposits. Prior to the XVII century, they remained under the control of the kind of Uesugi. Later Sado mines went to the house of the Tokugawa shoguns.
During the Edo period (1603-1867) Sado was under the direct control of the Shogunate.
March 1, 2004 all settlements of the island united to the city of Sado.