Which Byzantine emperor of the sixth century for a time won back parts of the former western empire?

Explication

The emperor meant here sent armies west from the eastern capital and recovered parts of Italy, North Africa and southern Spain for a time, although the gains slipped away within a few generations. The Frankish rulers listed as alternatives all ruled in the west and never held the eastern throne; the earliest of them reigned a generation before this emperor and the others more than a century and a half after him.