The diocese was established after the reforms of Diocletian and Constantine I in c. 314. In the year 407, the Rhine frontier was breached, and much of Gaul lost to barbarian tribes temporarily. Roman control over most of Gaul and the Rhineland was restored until the death of Valentinian III in 455. The only territory remaining in Roman hands after the 450s was in the northwest, the so-called "Domain of Soissons". After its fall to the Franks in 486 and the end of Roman administration in northern Gaul, the diocese can be said to have de facto ended.