Vikings were active in Brittany during the Middle Ages, even occupying a portion of it for a time. Throughout the 9th century, the Bretons faced threats from various flanks: they resisted full incorporation into the Frankish Carolingian Empire yet they also had to repel an emerging threat of the new duchy of Normandy on their eastern border by these Scandinavian colonists.
The Bretons therefore walked a tightrope between these two powers, often using one to mitigate the other's expansionist agendas. This would eventually lead to the downfall of the short-lived Kingdom of Brittany and a two-decade long occupation by the Norse only for this to be finally broken with support arriving from surprising sources.