now-lost letter. Ryūkyū can also be found in some stone inscriptions found on Okinawa Island. However, the un-Ryukyuan word remained alien to the Okinawans. There is no wonder that no single instance of Ryūkyū can be found in the ritual songs in the 22 volumes of the Omoro Sōshi, which reflects the Okinawan world-view. Over the course of centuries, the Okinawa-centered polity gradually expanded its sphere of influence to the north and to the south. In the second half of the 15th century, the kings themselves led military campaigns against Amami Ōshima and Kikai Island of the Amami Islands. Ryūkyū tightened control of the islands in the north after a major armed revolt on Amami Ōshima in 1537. As a result of Satsuma's conquest of Ryūkyū in 1609, however, the Amami Islands was ceded to Satsuma and have since then shared a much longer history with Satsuma than with Okinawa. As for the southern neighbors, local rulers of the Miyako and Yaeyama Islands are said to initiate contact with Ryūkyū at the end of the 14th century. In 1500, a military conflict among local rulers of the two island groups provoked a large armed intervention from Ryūkyū. Nevertheless, the relationship between Ryūkyū and the remote islands was only loosely maintained by tribute-paying local rulers. The situation changed after Satsuma's conquest of Ryūkyū in 1609. As an early modern polity, Satsuma introduced to Ryūkyū the system of controlling people within a strictly delimited territory. The Miyako and Yaeyama Islands were formally recognized as the heritable properties of the king (or the provincial governor as Satsuma called the king for decades following the conquest), and people there suffered from poll tax imposed by the Okinawan polity. Ryūkyū's territorial expansion, however, did not remove the word's prototypical association with Okinawa Island. The association remained particularly strong for Chinese Liuqiu. Since the Shi Liuqiu lu (1535), several memoirs of Chinese envoys to Ryūkyū have recorded glossaries of Okinawan words and phrases, where Chinese Liuqiu was routinely translated as Okinawa. For example, Liuqiu ren (琉球人) was translated as Okinawa hito (*okina(ː) pit͡ɕu, 倭急拿必周). Chinese envoys to Ryūkyū used the expression "arrive at Ryūkyū" (至琉球) only when they landed at the port of Naha or entered the Shuri Castle. They sometimes visited Kume Island on the route to wait for favorable wind conditions, but they did not utter the phrase there even though they knew that