Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
Relations of Rome to the North - The Country between the Alps and the Pyrenees - Conflicts with the Ligurians and the Salassi
From the close of the sixth century the Roman community ruled over the three great peninsulas projecting from the northern continent into the Mediterranean, at least taken as a whole. Even there however--in the north and west of Spain, in the valleys of the Ligurian Apennines and the Alps, and in the mountains of Macedonia and Thrace--tribes wholly or partially free continued to defy the lax Roman government. Moreover the continental communication between Spain and Italy as well as between Italy and Macedonia was very superficially provided for, and the countries beyond the Pyrenees, the Alps, and the Balkan chain--the great river basins of the Rhone, the Rhine, and the Danube-- in the main lay beyond the political horizon of the Romans.
We have now to set forth what steps were taken on the part of Rome to secure and to round off her empire in this direction, and how at the same time the great masses of peoples, who were ever moving to and fro behind that mighty mountain-screen, began to beat at the gates of the northern mountains and rudely to remind the Graeco-Roman world that it was mistaken in believing itself the sole possessor of the earth.
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