Settlement of the Venetian Lagoon
While many myths surround the first Venetians, most historians and archaeologists agree the lagoon and its islands were sparsely populated during the early Roman Empire with fisherman and duck hunters, likely trading with the cities of Aquileia, Altino, and Oderzo on the northern coast of the Adriatic Sea. San Francesco del Deserto, for example – an island in the northern lagoon shown by carbon dating to have first been inhabited in the 5th century – shows evidence of a Roman port where goods from the Adriatic were received and transferred to these towns, several miles west. The populations of these islands, meanwhile, were rather small and likely not year-round.
Between the 4th and 7th centuries, Eastern, Germanic, and Central Asian tribes migrated through Europe and into the territory of the Roman Empire. The Empire, whose fall is often attributed in part to these "barbarians," was not capable of defending northeastern Italy from invasion. As a consequence, the people of the Roman cities in the northern Adriatic, fleeing violence and chaos as these tribes swept through the region, sought safety in the islands of the Venetian lagoon.
Early waves of this migration into the lagoon came with the Visigoths and the Huns, who each sacked the wealthy Roman trading city of Aquileia, the former on their way to Rome in 402, and the latter under the command of Atilla the Hun in 452. In each case, the city's inhabitants fled their attackers, adept horsemen unfamiliar with seamanship, for the sea.
Though these early ventures into the lagoon were somewhat tentative -- with many Aquileians returning to the mainland when the danger passed – large, permanent settlements came in the 6th and 7th centuries with the invasion of the Lombards, a Germanic tribe from Northern Europe that is believed to have offered their military services to the Byzantine Empire in exchange for land in Italy. The Lombards crossed the Alps in 568, conquered the remaining cities of Oderzo and Altino in 639, and established a kingdom that would last until the end of the 8th century, leaving displaced mainland residents to become the first Venetians.
Sources:
Horodowich, Elizabeth. (Philadelphia). A Brief History of Venice. 2009: Running Press Book Publishers.
Image Source:
NASA Earth Observatory, via Wikimedia Commons