In 589 the bishop, St. Heliodorus, transferred the see to Sion, leaving the low-lying, flood-prone site of Octodurum, where the Drance joins the Rhone. Though frequently the early bishops were also abbots of Saint-Maurice, the monastic community was jealously watchful that the bishops should not extend their jurisdiction over the abbey. Several of the bishops united both offices: Wilcharius (764-780), previously Archbishop of Vienne, whence he had been driven by the Moors; St. Alteus, who received from the pope a bull of exemption in favor of the monastery (780); Aimo II, son of Count Humbert I of Savoy, who entertained Leo IX at Saint-Maurice in 1049.