It is believed that Celts, Gauls and Romans inhabited the valley long before the arrival of Christian monks. Records indicate that around 640 St Gondelbert founded the Benedictine monastery at Senones. The monks rapidly cleared the valley sufficiently to extend the settled land beyond Raon as far as Mount Donon, also including and the valley of the . The extent of this settlement approximately defines the territory that centuries later became the Principality of Salm-Salm after the settlement of 1751.