Settlements in the region remain small; certain strong leaders or chiefs organize alliances that bring several centers together for brief periods. The architecture continues to consist largely of buildings of circular or rectangular shape with river cobble foundations and retaining walls. Lashed cane covered with adobe and thatch make up the rest of the structures. In Costa Rica, stone sculpture takes on three-dimensional human form, gaining prominence over functional forms such as metates, probably the result of changes in ritual activity. While the quality and quantity of ceramic manufacture generally diminish except for some elite wares, production of fine gold objects is at a peak. The Taíno people, one of the groups inhabiting the islands of the Greater Antilles, create works of great individuality in a variety of mediums.