The Bretons have a recorded history of light cavalry since the eastern invasion of Francia of the Goths/Alani in the early 5th century. The Romans settled the Alani and Goths along the border with the Armoricans, the Notitia Dignitatum places them in Orleans, Poiters, Rennes, Alençon, Mayenne, Le Mans and Chartres. These areas became predominant Frank horse breeding areas in the 10th century and remained so up until the 19th century, 6 of the 8 French military light and heavy horse breeds come from the area).
John Wallace-Hadrill in his book Long Haired Kings, links the strength of the Breton feigned flight back to the Alani tactic in the 5th century, and the the overall use of heavy cavalry by the nobles. In several battles with the Franks, Vikings and Normans they used this tactic very successfully. By the 8th century the Breton border had moved to the west from the modern Mayenne river to the Vilane river, then back and forth for the next two centuries. Under Pepin the short, the Anjou-Maine Franks gained the territory, capturing the remaining Breton horse breeding areas almost entirely. By the 11th century the Anjou-Maine cavalry were also using the tactic of feigned flight, most famously allied with William the Conqueror along with the Bretons knights using feigned flight tactic at the battle of Hastings to break the Saxon sheildwall.