Western paintings of the Journey & the Adoration of the Magi usually depict 3 Magi, represented as kings, traveling to find the newborn Jesus by following a star; laying before him gifts of gold, frankincense, & myrrh; & lingering to worship him. Nowhere is the number of magi given in the Bible.
In Western Christianity, the arrival of the Magi at the site of Jesus' birth is called the Feast of the Epiphany, celebrated on January 6. The Orthodox Church commemorates the Adoration of the Magi on the Feast of the Nativity on December 25. Christian iconography has considerably expanded the simple biblical account of the Magi given in Matthew (2:1-11). The early church used the story to emphasize that Jesus was recognized, from his infancy, as king of the earth.
In the earliest depictions, the exotic Magi are shown wearing Persian dress of trousers & Phrygian caps with gifts held out before them. They echo centuries-older images of tribute-bearers from various Mediterranean & ancient Near Eastern cultures.
The earliest specific Magi images are from catacomb paintings & sarcophagus reliefs of the 4C. Crowns are first seen in 10C depictions, mostly in the West, where their dress had lost much of its Oriental flavor in most cases.
Later Byzantine images often show the Magi wearing small pill-box like hats or skull caps. The Magi were usually shown as about the same age until about this period, but then the idea of depicting the concept of 3 ages of man was introduced into the iconography.
Occasionally from the 12C, & very often in Northern Europe from the 15C, the Magi are also represent the 3 known parts of the world. Balthasar is often cast as a young African or Moor. An older Caspar is often portrayed with Asian features or dress. Melchior often comes to represent Europe & middle age.
From the 14C, large retinues are depicted accompanying the Magi. Their gifts often are contained in spectacular pieces of goldsmith work, & the Magi's clothes are more detailed. By the 15C, the Adoration of the Magi is often a complex exercise for the artist showing his ability to paint crowded scenes of people & animals, as well as the rich silks, furs, jewels, & precious gold of the Kings contrasting with the simple wood of the stable, the straw of Jesus's manger, & the simple, utilitarian clothing of Joseph & the shepherds. The animals depicted often include the ox & ass from the Nativity story & also horses, camels, dogs, & falcons of the kings & sometimes even birds in the rafters of the stable.
1470s Hieronymus Bosch. Hieronymus, or Jerome, Bosch, (c 1450-1516) Adoration of the Magi