One Gregorios was exarch of Ravenna in 666, but there might have been more than one exarch with that name.
An incomplete list of the Byzantine exarchs (vice-emperors) of the Exarchate of Ravenna.
The account of the Lombard conquest of the remaining parts of Byzantine Venetia in the 600s — from “Historia Langobardorum” by Paul the Deacon.
A list of some of the main events of the Lombard conquest of Byzantine Venetia and other parts of Italy.