Many pre-Columbian civilizations established characteristics and hallmarks which included permanent or urban settlements, agriculture, civic and monumental architecture, and complex societal hierarchies. Some of these civilizations had long faded by the time of the first significant European and African arrivals (ca. late 15th–early 16th centuries), and are known only through oral history and through archaeological investigations. Others were contemporary with this period, and are also known from historical accounts of the time. A few, such as the Mayan, Olmec, Mixtec, and Nahua peoples, had their own written records. However, the European colonists of the time worked to eliminate non-Christian beliefs, and Christian pyres destroyed many pre-Columbian written records. Only a few documents remained hidden and survived, leaving contemporary historians with glimpses of ancient culture and knowledge.