After the downfall of the
Western Roman Empire, Torcello was one of the first lagoon islands to be successively populated by those
Veneti who fled the
terra ferma (mainland) to take shelter from the recurring barbarian invasions, especially after
Attila the Hun had destroyed the city of
Altinum and all of the surrounding settlements in 452. Although the hard-fought
Veneto region formally belonged to the Byzantine
Exarchate of Ravenna since the end of the
Gothic War, it remained unsafe on account of frequent Gothic (Sarmatian) invasions and wars: during the following 200 years the
Lombards and the
Franks fuelled a permanent influx of sophisticated urban refugees to the island’s relative safety, including the Bishop of Altino himself. In 638, Torcello became the bishop’s official seat for more than a thousand years and the people of Altinum brought with them the
relics of
Saint Heliodorus, now the
patron saint of the island. Torcello benefited from and maintained close cultural and trading ties with
Constantinople: however, being a rather distant outpost of the
Eastern Roman Empire, it could establish
de facto autonomy from the eastern capital. Torcello rapidly grew in importance as a political and trading centre: in the 10th century it had a population often estimated at 10,000–35,000 people, with 20,000 the most commonly cited estimate. However, some recent estimates by archeologists place it at closer to a maximum of 3,000. In pre-Medieval times, Torcello was a much more powerful trading center than
Venice. Thanks to the lagoon’s salt marshes, the salines became Torcello’s economic backbone and its harbour developed quickly into an important re-export market in the profitable east-west-trade, which was largely controlled by Byzantium during that period. In three years, the
plague killed some 50,000 people. In 1630, the
Italian plague of 1629–31 killed a third of Venice's 150,000 citizens. A further serious issue for Torcello specifically was that the swamp area of the lagoon around the island increased by the 14th century, partly because of the lowering of the land level. Navigation in the
laguna morta (dead lagoon) was impossible before long and traders ceased calling at the island. The growing swamps also seriously aggravated
malaria. As a result, by the late 14th century, a substantial number of people left for the islands of
Murano,
Burano, or
Rialto (modern-day Venice). It now has a full-time population of just 10 people, including the parish priest, according to some sources, ==Sights==