Small groups arrived on the island when it was still attached to mainland. The island offers an exceptional density of traces (engravings) and megalithic monuments (menhirs, dolmens…), Bronze and Iron Age promontory fort.
At the end of the 6th century, St martin de Vertou and St Hilaire evangelised the island (named at that time ile d’OYA). Afterwards, St Colomban monks, from the Irish abbey of Bangor, could have built the 1st monastery dedicated to St Hilaire. The monks converted the wilderness of the island into a cultivated country. End of the 10th century, un second religious monument dedicated to St Etienne will be erected.
These monks are the first to start the construction of the roman church of St Sauveur. A village named also St Sauveur was built around it. It became the main town of the island, the main town where the governor used to live. During the Middle Ages and the never ending 100 year war, the lords of the island chose to build a castle off the wild coast. In 1355, the general emergency systeme failed. The English promptly conquered the island.
The English stayed on the island for 37 years until Olivier V de Clisson conquered back the island.
The island’s geographical location, near seaways was a key asset to become a port of call. Many islanders started coastal trade between Bordeaux and North of France. This activity flourished until the beginning of the 19th century despite many privateer attacks. During the 19th century, some islanders will turn to high seas navigation, others will become fishermen, tuna and sardine fishing. Canning industry developed, giving women work. The harbour, baptized in 1846 « Port-Joinville » will be the center of most islander activities. Between Wold War 1 and World War 2, motor boats will supersede sailing ships. These latter ships will disappear around 1950 .
Nowadays, the island's main goal is to maintain and enhance islander activities and population. Fishing activities have given way to tourism. Fishermen try to survive despite many regulations. The fish auction is still operational. Arts, crafts and agriculture are also new alternatives. These alternatives are necessary to maintain a population of 5000 inhabitants all year round on the island.