With few exceptions, the monoreligious villages range in population from 200 to 6,000 persons. Originally located for defensive purposes on steep mountain ridges, most were forced by the Dutch to relocate to the coast. The tightly clustered houses are often strung along one or more roads running parallel to the beach on a narrow strip of fairly flat land between the sea and mountains. The most prominent feature is either a large church or a mosque. There are two styles of housing. The first is the traditional wood-frame house with dirt floors, walls made from the stems of sago leaves ( gaba-gaba ), and thatched roofs also made of leaves of the sago palm ( atap ). This style is increasingly being replaced by concrete houses with plaster walls and corrugated iron roofs. The square spaces surrounding each house are usually meticulously free of any growth except for fruit- and nut-bearing trees and palms, some of which spread shade. Mostly along the beach there are rows of coconut palms. The land owned by each village is located beyond, in the mountains.