There was considerable variation in the permanency of Ainu settlements. Until the turn of the century, the basic pattern of the Sakhalin Ainu was a seasonal alternation of settlement between a summer settlement on the shore and a winter settlement farther inland. In the winter settlement, they built semisubterranean pit-houses. Ainu settlements were usually located along the shore, with houses in a single line parallel to the shore. The Kurile Ainu migrated even more frequently. In contrast, on Hokkaidō, permanent settlements were located along the rivers, which were rich in fish from mouth to source—an unusual situation for hunter-gatherers.
Most Ainu settlements, regardless of region, were small, usually consisting of fewer than five families. An exception was the Hidaka-Tokachi District on Hokkaidō, which enjoyed the most abundant natural resources and the densest population of all the Ainu lands. Here, especially along the Saru River, a few settlements housed about thirty families, and more than half the settlements in the valley exceeded five families.