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
There were instances even already of Roman burgesses acquiring landed property beyond the Roman frontier, and turning it to profit after the Italian fashion; there is mention, for example, of Roman estates in the canton of the Segusiavi (near Lyons) as early as about 673. Beyond doubt it was a consequence of this that, as already mentioned(24) in free Gaul itself, e. g. among the Arverni, the Roman language was not unknown even before the conquest; although this knowledge was presumably still restricted to few, and even the men of rank in the allied canton of the Haedui had to be conversed with through interpreters.
24. Cf. V. VII. Art and Science
Just as the traffickers in fire-water and the squatters led the way in the occupation of North America, so these Roman wine-traders and landlords paved the way for, and beckoned onward, the future conqueror of Gaul. How vividly this was felt even on the opposite side, is shown by the prohibition which one of the most energetic tribes of Gaul, the canton of the Nervii, like some German peoples, issued against trafficking with the Romans.
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Reference address : https://www.ellopos.net/elpenor/rome/5-07-subjugation-west.asp?pg=45