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
This new system, dependent on the Roman, not merely prevailed throughout the Massiliot, Upper Italian, and Illyrian territories; but these coins even penetrated into the barbarian lands on the north, those of Massilia, for instance, into the Alpine districts along the whole basin of the Rhone, and those of Illyria as far as the modern Transylvania. The eastern half of the Mediterranean was not yet reached by the Roman money, as it had not yet fallen under the direct sovereignty of Rome; but its place was filled by gold, the true and natural medium for international and transmarine commerce.
It is true that the Roman government, in conformity with its strictly conservative character, adhered--with the exception of a temporary coinage of gold occasioned by the financial embarrassment during the Hannibalic war(22)--steadfastly to the rule of coining silver only in addition to the national-Italian copper; but commerce had already assumed such dimensions, that it was able even in the absence of money to conduct its transactions with gold by weight. Of the sum in cash, which lay in the Roman treasury in 597, scarcely a sixth was coined or uncoined silver, five-sixths consisted of gold in bars,(23) and beyond doubt the precious metals were found in all the chests of the larger Roman capitalists in substantially similar proportions.
22. III. VI. Pressure of the War
23. There were in the treasury 17,410 Roman pounds of gold, 22,070 pounds of uncoined, and 18,230 pounds of coined, silver. The legal ratio of gold to silver was: 1 pound of gold = 4000 sesterces, or 1: 11.91.
Already therefore gold held the first place in great transactions; and, as may be further inferred from this fact, in general commerce the preponderance belonged to that carried on with foreign lands, and particularly with the east, which since the times of Philip and Alexander the Great had adopted a gold currency.
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Reference address : https://www.ellopos.net/elpenor/rome/3-12-management-land-capital.asp?pg=32