Treaty of Coulaines
The Treaty of Coulaines, named after the western French locality of Coulaines near Le Mans, was concluded in late 843 between Charles the Bald, king of West Francia, and his nobility and clergy. Since its validity was limited to West Francia, it has been interpreted as marking the start of a divergence between the respective legal orders of what would become the Kingdom of France and the Kingdom of Germany, just a few months after the two realms had been defined by the Treaty of Verdun.