Around 1590, Toyotomi Hideyoshi asked the Ryukyu Kingdom to aid in his campaign to conquer Korea. If successful, Hideyoshi intended to then move against China. As the Ryukyu Kingdom was a tributary state of the Ming dynasty, the request was refused. The Tokugawa shogunate that emerged following Hideyoshi's fall authorized the Shimazu family—feudal lords of the Satsuma domain (present-day Kagoshima Prefecture)—to send an expeditionary force to conquer the Ryukyus. The subsequent invasion took place in 1609, but Satsuma still allowed the Ryukyu Kingdom to find itself in a period of "dual subordination" to Japan and China, wherein Ryukyuan tributary relations were maintained with both the Tokugawa shogunate and the Chinese court.