Gusuku often refers to castles or fortresses in the Ryukyu Islands that feature stone walls. However, the origin and essence of gusuku remain controversial. In the archaeology of Okinawa Prefecture, the Gusuku period refers to an archaeological epoch of the Okinawa Islands that follows the shell-mound period and precedes the Sanzan period, when most gusuku are thought to have been built. Many gusuku and related cultural remains on Okinawa Island have been listed by UNESCO as World Heritage Sites under the title Gusuku Sites and Related Properties of the Kingdom of Ryukyu.

Okinawa Prefecture is the southernmost and westernmost prefecture of Japan. It has a population of 1,457,162 and a geographic area of 2,281 km2.