Earrings are jewelry attached to the ear through a piercing in the earlobe or some other external part of the ear (except in the case of clip earrings, which clip onto the lobe). Earrings are worn by both sexes. In western cultures, earrings have traditionally been worn primarily by women, although in recent decades, ear piercing has also become popular among men in North America, Europe, Asia and Africa. Ear piercing is one of the oldest known forms of body modification, with artistic and written references from cultures around the world dating back to early history. Early evidence of earrings worn by men can be seen in archeological evidence from Persepolis in ancient Persia. The carved images of soldiers of the Persian Empire, displayed on some of the surviving walls of the palace, show them wearing an ear ring.