The hypothesis is supported both by the passage of the Ancirano monument, unfortunately incomplete, in which the emperor recalls having pacified the whole West from Gades to ostium Albis, and even more from the fact that, as for Gaul, also for Germany Drusus had, between 12 and 9 a. C., consecrated the altar, which in due course should have constituted the religious and political center of the new province: and this altar had been established in the territory of the Ubîs on the left of the Rhine. its precise definition, had remained pending waiting to consolidate the conquest first.
According to computerminus, the defeat of Varus had overwhelmed every project: when, after the almost vain efforts of Tiberius and Germanicus, the extension of the borders to Elba was definitively renounced, it was resumed and implemented: except that the new provinces, while maintaining the name of Germany, they understood only a small part of this, a narrow strip of territory near the Rhine, almost entirely to the west of it, and expanded with the aggregation of some Celtic district: more than two real provinces, they could be considered as the military border territory of Gaul: with the which, and particularly with Belgica, they remained in fact closely linked. If the division of the command of the two armies immediately entailed a real organization of the two provincial territories, in the sense that the commanders of the legions also had the civil government, or if this organization came only later, at the time of the Flavî, as some have thought, one cannot yet say with certainty. What we can say is that the two commanders of the armies, and governors of the provinces, were always legates of consular rank, therefore superior to those of the three Gauls; that instead for the financial administration the two provinces always remained under the authority of the Belgica procurator, as from the customs point of view they always formed a single district with the Gauls. The Celtic tribes themselves included in them continued to send their representatives to the assembly of Lyons (see Germanyallia). Indeed, the boundaries of the two provinces between them and in relation to Belgica are not precisely determined: Upper Germany stretched from Lake Geneva at noon until, it seems, the confluence of the Vinxtbach with the Rhine between Confluentes (Koblenz) and Bonna (Bonn), to the north; to the west the districts of Elvezî, Sequani and Lingoni had been united with it: the seat of the governor was in Mogontiacum (Mainz). Lower Germany reached north to the sea, including the districts of the Tungri and Menapi west of the Rhine and the islands of the Batavians in the river delta; its capital was in Cologne.
As for the eastern borders, they were marked by the extension of Roman dominion towards the east, which varies according to the two provinces and according to the times. In Lower Germany, the abandonment of the conquest projects undoubtedly brought the border to the line of the Rhine, beyond which the Romans kept only the bridgehead of Cologne, represented by the castle of Deutz, some other fortified place along the course of the Lippe, and the lands of the Cannenefati and part of those of the Frisî, between the mouth of the Reno and that of the Ems. In Upper Germany, on the other hand, after the rout of Varo, possession of the Tauno was also maintained, which, opposite Mainz, commanded the lowlands of the Lower Main, from which invasions by the Germans were easier. At noon on the Main, on the right of the Rhine, the so-called first stretched out agri decumates, that is, it seems, a large area of land of dubious ownership, in which Roman and Celtic farmers could go to live (see in this regard the most recent study by E. Hesselmeyer, Was ist und was heisst Dekumatland ?, in Klio, XXIV, 1930, pp. 1-37). At the end of the century. I the area was incorporated into the territory of the empire, and mainly following the wars fought by Domitian against the Catti, the border was brought and consolidated somewhat further east, so as to include the entire Nicer basin (Neckar) up to the top Danube. The border, fortified by the Flavîs, and then again by Traiano and Adriano, ended up being marked by the line of the limes. In the Lorch locality this one broke off from the limes della Rezia and, running in an almost straight line from S. to N., reached the eastern end of the Tauno chain, turned north of this, closing it in the territory of the empire, and it then descended on the Rhine. Its total length was km. 382. It consisted of a continuous defense represented by an earthen wall, reinforced by poles (the Pfahlgrabendei Tedeschi), and preceded by a moat.