Early Roman Gaul came to an end late in the 3rd century. External pressures exacerbated internal weaknesses, and neglect of the Rhine frontier resulted in barbarian invasions and civil war. For a while Gaul, including Spain and Britain, was governed by a separate line of emperors (beginning with Postumus). However, there had still been no move to gain independence. In an attempt to save the Empire, Diocletian reorganized the provinces in 293, with the establishment of the "Diocesis Viennensis" in the south of Gaul, comprising the former Gallia Aquitania and Gallia Narbonensis. At the same time, Aquitania was divided into "Aquitania Prima", with its see (capital) in "Avaricum Biturigum" (Bourges), "Aquitania Secunda" (see – "Burdigala"; the later Bordeaux) and "Aquitania Tertia", better known as "Novempopulania" ("land of the nine peoples"), with its see in "Elusa" (Eauze). "Novempopulania" originated in boundaries set up by Caesar for the original Aquitania, who had kept some kind of separate sense of identity (Verus' mission to Rome aimed at demanding a separate province). After this restructuring, Gaul enjoyed stability and enhanced prestige. After the trans-Rhine invasion December 31 406 by 4 tribes (Alans, Sueves, Asding and Siling Vandals), the offices of the Gallic prefecture were moved from Trier to Arles even though the Rhine frontier was subsequently restored and under Roman control till 459 when Cologne was taken by the Franks. Roman attention had been shifted to the south to try to control the invaders and keep them from the Mediterranean, a policy which failed after the Vandals started to harass the coasts from their bases in southern Spain from the early 420s.