Most people think that the Mediterranean coasts have been settled for a long time and that the local communities of Cinque Terre and other coastal towns were centered around the sea.
Yes, the second part of this statement is true since trade and commerce happened mostly by sea, but the first part of the above sentence isn't true. And this is because with the exception of a few centuries under the extensive Pax Romana throughout the Mediterranean basin, living on the coast or anywhere in sight of the ocean wasn't considered safe.
What we know today, as the Italian Riviera was plagued by pirates, slave traders, and marauders, to name a few of the evils that abounded. Around 1000 AD came the rise of the Italian cities of Pisa, Genoa, Venice and Amalfi and this created a new century of "pax" (peace) which allowed farmers and fishermen to begin to inhabit and develop their trades along the coasts of the Italian and French Rivieras.