Ainu Chashi Architecture

Chashi, from the Ainu word casi meaning palisade or palisaded compound, is the term used for the hilltop fortifications built by the Ainu people of Hokkaido, southern Sakhalin and the Kuril Islands. More than five hundred and twenty such structures have been identified, concentrated in eastern Hokkaido, enclosed by wooden palisades roughly one and a half times a person's height and containing two or three houses along with wooden scaffolding at the corners for lookout purposes. A few sites date to the Muromachi period, including the Toya casi near present-day Kushiro, but most were built in the early seventeenth century, which scholars connect to increased competition for resources as trade with the Japanese intensified. Beyond defense against rival Ainu groups, chashi also functioned as gathering centers, ritual sites and visible symbols of chiefly power.