What is today called the Caer Hylennia used to be called the Burgus Tyberian. A fort constructed south of Rhold and closer to the Rus, the fortress was a means of resupplying convoys and military personnel enforcing order (and later attempting to reclaim) Peramul. The fort lost its vitality toward the 800s in the third era due to the sloth of the military and strategical lack of importance.