Five hundred years of Ryukyuan history (12th-17th century) are represented by this group of sites and monuments. The ruins of the castles, on imposing elevated sites, are evidence for the social structure over much of that period, while the sacred sites provide mute testimony to the rare survival of an ancient form of religion into the modern age. The wide- ranging economic and cultural contacts of the Ryukyu Islands over that period gave rise to a unique culture.