Gusuku are existent over a wide range, extending from the Amami islands to the Okinawa islands and Sakishima islands.

Many existing Gusuku retain vestiges of the ancient Ryukyus in their appearance, symbolized by stonewall enclosures and castle ramparts. When, by whom and for what purposes were they built?

In clearing up the history of the Gusuku, the as yet unclear portion relates to clarifying issues surrounding the dawn of the Ryukyus.

At present, the Chinese character for castle (romanized as Shiro or Jo) is generally used to write the term Gusuku. When used it is expressed as "the such- and-such castle ruins." However, for example, the outward appearance is quite different when compared to what are termed "castles" on the Japanese mainland. This can be comprehended by tracing back through the history of the once independent Ryukyu Islands.