Throughout the Maprik area there were continuous population movements, not only the general south-to-north pattern but also minor movements within the region. These movements generally involved small kin groups who affiliated themselves with an already existing settlement or who formed new settlements elsewhere. Only after warfare ceased and peace was imposed did these movements stop and villages become relatively permanent. In the north, the Abelam probably absorbed many Arapesh people—or, rather, killed them or chased them off and took their territory. This high mobility is still reflected in the alliances of small groups in hamlets with other groups in other hamlets. Abelam villages vary in size. They are much smaller in the south with only 50 to 80 people. In the north, they now number up to 1,000 people. In the south, settlements are basically hamlets; in the north they are villages, preferably situated on a hill ridge, consisting of forty to fifty hamlets. Each is autonomous, at least concerning their relations with other settlements. Villages are Structured as an association of hamlets who have formed something like a localized league. The village territory is generally divided into "upper" and "lower" topographical units. The structure of villages in the north is complex. Through rituals for different root crops, yam festivals, and initiation, the different major hamlets—each of which has a special role within this network of rituals—are bound together. Buildings such as storehouses, sleeping and dwelling houses, menstruation huts, and the towering ceremonial houses are built on the ground in a triangular plan. They consist more or less of a roof with a ridgepole gently sloping down from the front towards the back. Most spectacular are the ceremonial houses ( korambo ) with a large ceremonial ground ( amei ) in front of it. Only major hamlets have a korambo, which may be up to 25 meters tall, with a painted facade. The korambo and amei are considered the village center but larger villages may have up to ten or fifteen such centers. The building material is timber and bamboo for the inner structure; sago palm fronds are used for the thatch. Lashing techniques are elaborate.