 During the Jōmon period, the sea level was higher than now and all the flat land in Kamakura up to Tsurugaoka Hachiman-gū and, further east, up to Yokohama's Totsuka-ku and Sakae-ku was under water.Thus, the oldest pottery fragments found come from hillside settlements of the period between 7500 BC and 5000 BC.In the late Jōmon period the sea receded and civilization progressed.