Soooooooo, this question is underpinned by an assumptions about money and exchange that common among laymen. But I’ll get to that in a minute. The short and simple answer to your question is that, in Western Europe prior to the Carolingian Empire, there was not a powerful, centralized state with sufficient reserves of bullion to issue a currency that consumers could trust to have consistent previous metal content.

But let’s get to the greater point I want to make that is connected to incorrect assumptions about economic history that are rooted in the idea that a moneyed economy naturally progresses from a so-called barter economy. And in the case of this question, early medieval Europe devolved back into a supposed “barter” economy. But this evolutionary model of economic exchange is deeply flawed at best, and flat-out wrong at worst, and we have ample evidence of this. Adam Smith, the origin of this assumption, made many points that are demonstrably incorrect about economic history. Graeber’s popular history of debt is certainly flawed, but it’s a good introduction to these issues. To simplify the point I want to make, for most of human history, monetary exchange, when it existed, has existed side-by-side with non-monetary exchange, whether this takes the form of networks of credit based on social capital—hey neighbor, I have no food, can you hook me up and I’ll get you back—or exchange of products. And monetary exchange, when it existed, was less common than non-monetary exchange for most of human history. An interesting aside, I was reading Steven Hahn’s history of the United States in the 19th century, A Nation Without Borders yesterday, and he notes that shopkeepers, even those with extensive contacts in the finance world of the North East, would accept non-monetary items of value in exchange for goods—literally “produce that is good to eat” was the wording Hahn found repeatedly.

So, if we look to Late Antiquity, the era before the Early Middle Ages, the we find an era with substantially more coinage in circulation than the early Middle Ages, and this has to do with the reasons laid out in the first paragraph. The Roman Empire, at least before the crises of the third century, was powerful, had access to massive amounts of billion, and could enforce a standardized currency. We have that ample evidence of this, both archaeological and literary. For example, we have a letter that the late Roman senator, Symmachus, wrote while escorting literal cartloads of bullion as a gift to the new emperor stationed at Trier. This cash would have been used to pay off the army. And I suspect that that was where quite a bit of late Roman specie ended up—the hands of soldiers. That said, non-monetary exchange seems to have been prevalent throughout the Roman world. In his article “A Revisionist View of Roman Money,” WV Harris points out that rents and taxes were widely paid “in-kind” throughout the empire, even in the highly developed province of Egypt. And it is important to remember that the Roman Empire was incredibly RURAL. Much has been made of the amazing cities that Rome left behind and the way provincial elites exercised authority and engaged in politics in these “miniature” Romes. That said, a disproportionately large amount of people lived in rural communities, often on massive estates. Furthermore, as far as know, these inhabitants were not all slaves as very traditional historiography suggests (though I would eagerly await clarification on this matter). Two good books that I have found helpful for learning about Roman Rural society are Kehoe’s Law and the Rural Economy in Ancient Rome, which reveals the variety of tenancy agreements outside of slavery, and Harper’s Slavery in the Ancient Roman World, which is excellent. To assume that it would have been possible for these tenants, who are widely paying rents in kind, to use currency in day-to-day interactions seems a flawed assumption.

Where we could see specie entering into day-to-day interactions would be through the hands of wage laborers, who would have been present in larger cities. And we do not see larger cities capable of supporting wage labor re-emerge in medieval Europe until at least the 11th century, and even this is very early and, again, dependent on the presence of a stable currency. But again, in both the Roman and medieval cases, wage labor can only manifest where there is a large enough agglomeration of humans and capital to support them, which is basically going to happen in cities. Regardless, in both the Roman Empire at its height, and the high Middle Ages, when the population of Western Europe was at its highest level prior to industrialization, the rural economy would have been operating largely without specie.

To conclude, the most important difference between the early medieval and late antique economies has to do with large scale networks of credit based on trade where goods worth thousands of pounds of precious metals, recorded as records of account, were being exchanged. Indeed, even in places where long distance trade products existed in Northern Europe during the early Middle Ages—namely emporia—these sites were limited and tied to elite gift exchange and would not have fostered large scale currency exchange (see the chapter on emporia in the sixth century: Population Distribution and demand.