The open-field system was the prevalent agricultural system in much of Europe during the Middle Ages and lasted into the 20th century in Russia, Iran, and Turkey. Each manor or village had two or three large fields, usually several hundred acres each, which were divided into many narrow strips of land. The strips or selions were cultivated by peasants, often called tenants or serfs. The holdings of a manor also included woodland and pasture areas for common usage and fields belonging to the lord of the manor and the religious authorities, usually Roman Catholics in medieval Western Europe. The farmers customarily lived in separate houses in a nucleated village with a much larger manor house and church nearby. The open-field system necessitated co-operation among the residents of the manor.