Japanese invasion (1609)

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 occupation of the Ryukyus occurred fairly quickly, with a minimum of armed resistance, and King Sho Nei was taken as a prisoner to the Satsuma domain and later to Edo—modern day Tokyo. When he was released two years later, the Ryukyu Kingdom regained a degree of autonomy; however, the Satsuma domain did seize control over some territory of the Ryukyu Kingdom, notably the Amami-Oshima island group, which was incorporated into the Satsuma domain.
 

The Ryukyu Kingdom found itself in a period of "dual subordination" to Japan and China, wherein Ryukyuan tributary relations were maintained with both the Tokugawa shogunate and the Ming Chinese court. Since Ming China prohibited trade with Japan, Satsuma domain, with the blessing of the Tokugawa bakufu (shogunal government), used the trade relations of the kingdom to continue to maintain trade relations with China. Considering that Japan had previously severed ties with most of the European countries except the Dutch, such trade relations proved especially crucial to both the Tokugawa bakufu and Satsuma han which would use its power and influence, gained in this way, to help overthrow the shogunate in the 1860s.

The Ryukyuan king was a vassal of the Satsuma daimyo, but his land was not counted as part of any han (fief): up until the formal annexation of the islands and abolition of the kingdom in 1879, the Ryukyus were not truly considered part of Japan, and the Ryukyuan people not considered Japanese. Though technically under the control of Satsuma, Ryukyu was given a great degree of autonomy, to best serve the interests of the Satsuma daimyo and those of the shogunate, in trading with China. Ryukyu was a tributary state of China, and since Japan had no formal diplomatic relations with China, it was essential that Beijing did not not realize that Ryukyu was controlled by Japan—if they did, they would end the trade. Thus, ironically, Satsuma—and the shogunate—was obliged to be mostly hands-off in terms of not visibly or forcibly occupying Ryukyu or controlling the policies and laws there. On top of that, in a strange way, it benefited all three parties involved—the Ryukyu royal government, the Satsuma daimyo, and the shogunate—to make Ryukyu seem as much a distinctive and foreign country as possible. Japanese were prohibited from visiting Ryukyu without shogunal permission, and the Ryukyuans were forbidden from adopting Japanese names, clothes, or customs. They were even forbidden from acknowledging their knowledge of the Japanese language during their trips to Edo; the Shimazu family, daimyo of Satsuma, gained great prestige by putting on a show of parading the King, officials, and other people of Ryukyu to and through Edo. As the only han to have a king and an entire kingdom as vassals, Satsuma gained significantly from Ryukyu's exoticness, reinforcing that it was an entire separate kingdom.

When Commodore Matthew Calbraith Perry sailed to Japan to force Japan to open up trade relations with the United States in the 1850s, he first stopped in the Ryukyus, as many Western sailors had before him, and forced the Ryukyu Kingdom to sign Unequal Treaties opening the Ryukyus up to American trade. From there, he continued on to Edo.

Following the Meiji Restoration, the Meiji Japanese government abolished the Ryukyu Kingdom, formally annexing the islands to Japan as Okinawa Prefecture in 1879. The Amami-Oshima island group which had been integrated into Satsuma domain became a part of Kagoshima prefecture. King Sho Tai, the last king of the Ryukyus, was moved to Tokyo and was made a Marquis (see Kazoku), as were many other Japanese aristocrats, and died there in 1901. Qing China made some diplomatic protests to the Japanese government, but these proved to have little effect.