State and Coinage in the Late Republic and Early Empire

TLDR: From the time of the introduction of the denarius system onwards, Roman currency gradually spread over all, or nearly all, the regions under Roman rule, in the wake of their progressive integration into the Empire as mentioned in this paper.

Abstract: From the time of the introduction of the denarius system onwards, Roman currency gradually spread over all, or nearly all, the regions under Roman rule, in the wake of their progressive integration into the Empire. Partly, the denarius replaced previous currencies, partly it brought about the monetization of areas not yet monetized. It was therefore the most striking feature, and indeed the logical premise, of the economic unification of the Empire (in so far as one can speak of such a unification). Until the Severan age, the Roman monetary system remained stable, notwithstanding the widening of the area it covered and the various changes it underwent—the introduction of new denominations and new metals, the retariffing of some elements in relation to each other, the transformation of the physical quality of the coins, for instance through debasement: in fact, there were no sudden and considerable rises of prices and Roman currency almost always enjoyed automatic confidence.