Ryukyuan missions to Edo

Over the course of Japan's Edo period, the Ryūkyū Kingdom sent eighteen^[1] missions to Edo (琉球江戸上り, ryūkyū edo nobori, "lit. 'the going up of Ryūkyū to Edo'), the capital of Tokugawa Japan. The unique pattern of these diplomatic exchanges evolved from models established by the Chinese, but without denoting any predetermined relationship to China or to the Chinese world order.^[2] The Kingdom became a vassal to the Japanese feudal domain (han) of Satsuma following Satsuma's 1609 invasion of Ryūkyū, and as such were expected to pay tribute to the shogunate; the missions also served as a great source of prestige for Satsuma, the only han to claim any foreign polity, let alone a kingdom, as its vassal.^[3]