The Byzantine Mosaic Tradition in Italy

Mosaic artists from Constantinople were active in Italy over several centuries, leaving marvellous works which have survived the turmoil of the times.
Here is the Byzantine Emperor Justinian and his wife, Theodora with her court; created in Ravenna in the sixth century

Then, half a millenium later; King Roger of Sicily is portrayed crowned by Christ. This is in Palermo, from the early twelfth century.

Justinian's generals succeeded in reconquering Italy from the Goths, in an attempt to restore the Roman Empire, but this came at enormous cost in the devastation of the country. In later centuries, the Lombards occupied northern Italy, and the holy Roman Empire was established by Charlemagne and his successors. 
    Meanwhile Arab forces conquered Sicily. Roger overran the island and established a spectacular but short-lived kingdom which combined Greek, Arab, Norman and Jewish elements. 

In fact, both of these monarchs' families were flagrant interlopers. Justinian succeeded to the Imperial title on the death of his uncle, Justin, a peasant soldier from the Balkans who had risen to the throne through the army. Roger was from the second generation of a family of Norman knights, the de Hauteville brothers, who terrorised sounthern Italy in the 11th century.