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
Religion-- New Gods
We are less able to trace the progress of the religious conceptions of the Romans during this epoch. In general they adhered with simplicity to the simple piety of their ancestors, and kept equally aloof from superstition and from unbelief. How vividly the idea of spiritualizing all earthly objects, on which the Roman religion was based, still prevailed at the close of this epoch, is shown by the new "God of silver" (-Argentinus-), who presumably came into existence only in consequence of the introduction of the silver currency in 485, and who naturally was the son of the older "God of copper" (-Aesculanus-).
The relations to foreign lands were the same as heretofore; but here, and here especially, Greek influences were on the increase. It was only now that temples began to rise in Rome itself in honour of the Greek gods. The oldest was the temple of Castor and Pollux, which had been vowed in the battle at lake Regillus(17) and was consecrated on 15th July 269.
17. Cf. V. V. The Hegemony of Rome over Latium Shaken and Re-established
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Reference address : https://www.ellopos.net/elpenor/rome/2-08-law-religion-army-economy-nationality.asp?pg=14