The Exarchate of Ravenna was an ad hoc organisation of the Byzantine dominions in Italy, established c.584, in the face of the Lombard invasion and gradual conquest of much of the Italian peninsula.
The Chronicon Altinate contains an apocryphal account of how duke Paulicius was killed in a factional fight between people from Equilo and Heraclia.
Venetia existed within the Exarchate of Ravenna, as part of the Byzantine Empire, and what happened in the Exarchate mattered to Venetia.
The account of the election of the first three doges of Venice (Pauluccio, Marcello and Orso), from the anonymous “Chronicon Altinate”.