Although the ancient Egyptians decorated their royal artifacts with an ascendancy of colored gemstones, glass and faience, this was not an enameling technique. Rather a form of mosaic. Early Roman enamels were also of this type where they used pieces of multicolored glass (“millefiori”) and placed them in a predestined pattern. The gaps in between were filled with a glass powder which, after heating, fused the millefiori smalti together. Though this is similar to enameling, the glass did not fuse to the metals. It was only later that they started to place the smalti in a type of tube setting and then punching the metal over the glass, followed by heating at the appropriate temperatures which caused a fusion to the surrounding metal, that we can speak of a true enamel.
During the Byzantium era cloisonné enamel flourished in the Eastern Roman Empire as well as in many Celtic areas (as Gaul and in Britain). This technique has been known for over two millenniums and it could well have spread over Europe during the migration period which preluded the middle ages.