Unlike the growing interaction that marked the African, Asian, and European worlds, the Americas and Oceania remained largely isolated. Any contact before 1492 was more accidental and momentary than planned or continuous. Nevertheless, the peoples of North and South America created large empires with cultural and religious concepts that, because of the isolation of these societies, were unique. The societies of Oceania existed in even greater isolation. Despite this isolated existence, the peoples of Oceania eventually developed structured agricultural societies and chiefly political structures.