In 600 000 BC, the first signs of human life appeared in Brittany.

Neolithic farmers and shepherds began to erect the first megalithic monuments.

The arrival of bronze marks a period of growth, while the introduction of iron marks the integration of Celtic civilization.

The peninsula benefited from the Roman peace, Romanization did not erase the use of the Gaulish language, nor the old religious traditions.

In the 5th century, migrations of populations fleeing disorders in Brittany settled in Armorica, turning it into a new Brittany. The Bretons, with their language, Christianized the region. Despite initial autonomy, the Frankish attempt to subdue them in the 8th century was overcome with the Carolingian recognition of the Breton prince's title in 851. Nevertheless, Frankish customs infiltrated Brittany, and succession crises and Norman aggressions ended Breton royalty at the beginning of the 10th century.

In Brittany, there was agricultural growth and urban development overseen by various authorities, including lords, ecclesiastics, and laymen. Although the duke had great power, it could not escape the control of the Plantagenet kings of England in the second half of the 12th century, before passing into the hands of a dynasty linked to the kings of France in 1213. In 1341 , the duchy plunged into a long war that favored the Montfort family. The new dukes sought to turn the duchy into a quasi-state, while Brittany experienced some prosperity. Towards the end of the 15th century, the power of the duke collided with the restored power of the royal state, and the Edict of Union of 1532 confirmed the accession of Brittany to the kingdom of France.