The Magi most frequently appear in European art in the "Adoration of the Magi"; less often in the "Journey of the Magi" has been a popular subject in art, and "topos", and other scenes such as the "Magi before Herod" and the "Dream of the Magi" also appear in the Middle Ages. In Byzantine art they are depicted as Persians, wearing trousers and phrygian caps. Crowns appear from the 10th century. Despite being saints, they are very often shown without halos, perhaps to avoid distracting attention from either their crowns or the halos of the Holy Family. Sometimes only the lead king, kneeling to Christ, has a halo the two others lack, probably indicating that the two behind had not yet performed the act of worship that would ensure their status as saints. Medieval artists also allegorised the theme to represent the three ages of man. Beginning in the 12th century, and very often by the 15th, the Kings also represent the three parts of the known (pre-Columbian) world in Western art, especially in Northern Europe. Balthasar is thus represented as a young African or Moor, and Caspar may be depicted with distinctly Oriental features.