Japanese gardens have their roots in the national religion of Shinto, with its story of the creation of eight perfect islands, and of the "shinchi", the lakes of the gods. Prehistoric Shinto shrines to the "kami", the gods and spirits, are found on beaches and in forests all over the island. They often took the form of unusual rocks or trees marked with cords of rice fiber ("shimenawa") and surrounded with white stones or pebbles, a symbol of purity. The white gravel courtyard became a distinctive feature of Shinto shrines, Imperial Palaces, Buddhist temples, and Zen gardens. Although its original meaning is somewhat obscure, one of the Japanese words for garden—niwa—came to mean a place that had been cleansed and purified in anticipation of the arrival of kami, the deified spirits of Shinto, and the Shinto reverence for great rocks, lakes, ancient trees, and other "dignitaries of nature" would exert an enduring influence on Japanese garden design.