The magi ('wise men') were traditionally astrologers of the Persian court and priests of the cult of Mithras, but were later redefined as kings. In the early Middle Ages they were given names, and, from the 15th century, Balthazar, the black magus/king, became a familiar figure in European images of the Adoration of Christ at his birth. The three magi/kings were often depicted as representatives of the three known continents - Europe, Asia and Africa (America only became known to Europeans at the end of the 15th century). They were also meant to represent the three ages of life - old age, middle age and youth. The black magi/king was usually depicted as the youngest of the three, as in this example.