The decoration of these tiles was achieved by carving away most of the layer of purplish black glaze that originally covered the entire surface, leaving only the inscription and the vegetal scrolls in dark relief. The technique is called zilij in Morocco, where this type of tile was made for decorative architectural friezes from the fourteenth through the seventeenth century. Although it is not possible to identify the building these tiles once embellished, it must have been an important secular structure in Fez or Marrakesh. To judge from the color of the glaze, which was common in the early period of zilij tile production, the frieze was probably assembled in the fourteenth or early fifteenth century. Delicate spirals terminating in elegant split palmettes provide a background for the Arabic inscription, which was copied in a cursive calligraphy similar to that known as thuluth. Apparently, the frieze repeated the same four words over and over, the second and fourth of which rhyme; the cheerful and welcoming phrase can be translated as "What excellent companions are happiness and good fortune!"