In heathen times chieftains were both political and religious leaders, tasked to use their luck to secure the people fred (translated "good times" - nowadays actually the word for peace). Luck was considered the sign of the leader. He was appointed leader, who possessed a great luck. But the luck could also abandon its bearer, and chose someone else as carrier.
The Ostrogoths settled in Italy, the Franks in northern Gaul, the Burgundians in Provence, the Visigoths in southern Gaul and Spain, the Vandals in Africa and the western Mediterranean, and the Angles and Saxons in England.
As western Europe fell to the Germanic invasions, imperial power shifted to the Byzantine Empire, that is, the eastern part of the Roman Empire, with its capital at Constantinople.
Justinian was also aided by his wife, Theodora (c.500-547), the daughter of a bearkeeper at the Hippodrome, and no less ambitious than her husband.