The size of the Ryūkyū kingdom (now part of Japan) changed over time, but its main territory was roughly equivalent to modern Okinawa. The capital was located in the Naha, an island in Okinawa islands. The Ryūkyū kingdom was a tributary state of China for generations and, as a result, they set up a series of positions for interpreters (tsūji) in their administrative system, the highest rank of which was the Shikin taifu 紫金大夫 [Master Purple-Gold]. Ryūkyū interpreters were mainly Chinese immigrants who arrived in Ryūkyū during the reigns of Hóngwǔ 洪武 (1368–1398) and Y…