The lagoon was settled in Antiquity, and in the 600s, there were numerous known towns, and several important cities. Venice, however, was not one of them.
There were more lagoons on the coast of Venetia than what exists today, and even the lagoon landscapes were different. In fact, had it been left to nature, there would have been no lagoons today.
Following the Lombard invasion and conquest of Venetia, a part of the Venetian population of the mainland cities fled or left for the settlements in the nearby lagoons.
Why did the Lombards decide to invade Byzantine Italy in 568? A popular story was the Byzantine general Narses, who had just retaken Italy for the empire, invited them. Was Narses a traitor to the empire?
The Lombard invasion of Byzantine Italy in 568 was a pivotal event in Venetian history, as it kicked off the movement towards a distinct Venetian society, culture and, ultimately, state.