The Celtic area was occupied by the Romans from 58 BC until the 5th century AD when the Bretons, coming from what is now Great Britain, claimed the land.
In 1213, the Bretons were ruled by a Capetian and thus eluded Plantagenet domination. The entire duchy was run by descendants of Pierre I of Dreux until the War of Succession, won by Jean de Montfort (later Duke Jean IV).
Brittany became a French region in 1491 when Anne, the daughter of François II, married Charles VIII. This alliance was further strengthened when Claude of France, born from Anne’s second marriage, offered Brittany as her dowry when she married François I, future King of France, in 1514. The houses of parliament were built in Rennes in 1553, transformig the city into a major administrative centre.
The department’s economy began to flourish during the 19th century after the opening of the Ille-et-Rance canal in 1838 and the inauguration of the Paris-Rennes railway line. The first seaside resorts were built at this time.
The Ille-et-Vilaine département was almost renamed twice in the last three decades but both propositions (Marches de Bretagne and Haute Bretagne) were rejected.