By Open Chronicle History Desk
For generations, historians have explained the rise of Rome through armies, conquest, political institutions and extraordinary infrastructure. A new large scale study of Roman coin circulation adds another dimension to that story: Rome’s durability depended not simply on conquering territory, but on connecting conquered regions to an increasingly integrated economic system.
Researchers at the University of São Paulo analysed archaeological evidence from approximately four million coins, reconstructing patterns of monetary circulation across the Roman world between 155 BCE and 2 CE, a period spanning the final generations of the Roman Republic and the emergence of the Augustan order.
Their findings suggest a striking sequence. Roman armies helped introduce monetary circulation into newly conquered territories, but military occupation alone did not create lasting integration. Once roads, cities, markets, administrative institutions, religious centres and civic structures developed, economic activity increasingly sustained the circulation of Roman money.
In simplified terms, the army opened the network; the economy made it permanent.
Reading Roman History Through Millions of Coins
The research represents a broader transformation occurring within archaeology.
Ancient historians traditionally depended heavily on surviving literary texts, inscriptions, monuments and archaeological excavations. Digitisation now allows researchers to combine enormous collections of material evidence that were previously scattered among museums, catalogues, libraries and individual archaeological projects.
Coins are particularly valuable.
A recovered coin can potentially tell researchers where it was minted, approximately when it was produced and where it was eventually discovered.
One coin provides a fragment of information. Millions of coins can reveal networks.
Professor Eduardo Amaral Haddad, of the University of São Paulo’s School of Economics, Business and Accounting, and Inácio Fernandes Araújo, now at USP’s Luiz de Queiroz College of Agriculture, applied techniques normally associated with regional economics, economic geography, spatial analysis and geographic information systems to this archaeological evidence.
Their peer reviewed research, titled Economic footprints: mapping coin circulation and economic networks in ancient Rome, was published in Humanities and Social Sciences Communications on 9 June 2026.
From an Academic Curiosity to a Roman Economic Map
The origins of the project were surprisingly informal.
Haddad’s interest began during a 2014 sabbatical at Princeton University. Although working primarily in economics, he attended seminars organised by the Department of Classics.
One presentation examined how shipwrecks and pottery fragments could be used to reconstruct ancient Mediterranean trading networks.
The idea suggested an intriguing possibility.
If archaeological evidence could reconstruct trade, perhaps the analytical methods used by modern regional economists could also reveal how money moved through the ancient world.
Haddad subsequently encountered a catalogue of Roman coins containing precisely the type of information necessary for such an experiment: minting dates, production locations and archaeological find sites.
What began as an intellectual side project eventually developed into sustained interdisciplinary research. Haddad even undertook graduate study of the ancient Mediterranean through the University of Leicester to deepen his understanding of the historical environment he was attempting to model.
Building a Database of Roman Money
The scale of the analysis was made possible by the digitisation of numismatic and archaeological collections.
The principal source identified by the researchers was Coin Hoards of the Roman Republic Online, supplemented by several digital resources capable of reconstructing ancient geography and transportation.
Among them was ORBIS, developed at Stanford University, which models movement through Roman roads, rivers and maritime routes and can estimate travel time and costs between locations.
The researchers also used the Pleiades gazetteer and Roman road network data to provide geographical information about ancient settlements, ports and transport routes.
After extensive data curation, their analytical dataset contained approximately four million coins, organised into 24,646 hoards and representing 5,167 minting site and discovery site pairs.
That distinction matters.
The researchers were not simply plotting millions of isolated objects on a map. They analysed archaeological assemblages and relationships between where money originated and where it eventually entered the archaeological record.
Following the Money
One of the first questions was fundamental.
Were Roman coins scattered more or less randomly across the Mediterranean, or was there an identifiable geographical structure to their distribution?
The evidence strongly supported the second possibility.
The researchers found statistically significant concentrations associated with major routes of movement and commerce.
Then another pattern emerged.
Coins originating in Rome showed identifiable geographical diffusion through the expanding Roman system.
Roads, ports and cities were therefore more than physical infrastructure. They acted as channels through which monetary and economic relationships could spread.
Rome Between 155 BCE and 2 CE
The period examined by the study was one of the most consequential transformations in Roman history.
Rome had emerged victorious from the Punic Wars and was expanding across the Mediterranean.
Roman power reached into Hispania, Greece, North Africa, Gaul, the Balkans and the eastern Mediterranean.
But conquest generated enormous political and economic pressures.
Wealth flowed towards Italy. Enslaved populations were transported across the Mediterranean. Military commands became increasingly important politically. Competition among Roman elites intensified.
Eventually, the Republic descended into repeated civil wars.
Marius, Sulla, Pompey, Julius Caesar, Mark Antony and Octavian belonged to successive generations of political and military struggles that fundamentally altered the Roman state.
In 27 BCE, Octavian became Augustus, traditionally marking the transition from Republic to Empire.
The researchers’ period therefore captures something more significant than territorial expansion. It encompasses the transformation of Rome from a city dominated republic into the centre of a Mediterranean political and economic system.
Reconstructing an Economy That Left No National Accounts
Modern economists can study GDP, taxation, household expenditure, trade statistics, wages and government budgets.
No comparable statistical archive exists for Republican Rome.
The researchers therefore constructed an approximate economic framework based on archaeological and historical scholarship.
Their model drew inspiration from social accounting matrices, tools used by economists to describe transactions between different sectors and participants within an economy.
For ancient Rome, the researchers considered relationships involving groups and institutions such as government, households, landowners, merchants, enslaved people and the army.
They also differentiated economic activity involving food, raw materials, manufactured products and luxury goods, some of which travelled across much greater distances.
This does not mean historians suddenly possess a precise balance sheet for the Roman Republic.
Rather, the framework provides a way of testing how different forms of economic activity might relate to the archaeological distribution of money.
The Monetisation of Roman Life
Another crucial historical development was the increasing importance of coinage itself.
Not every transaction in Republican society involved money.
Payments and exchanges could occur in kind, particularly in agricultural and other local economic relationships.
Over time, however, coin became increasingly important in transactions involving the state, military supply and other economic activities.
This process of monetisation left material evidence.
If more transactions required money, then the circulation of coins should become more extensive and economically embedded.
The archaeological record appears to preserve traces of that transformation.
Coin hoards can therefore become more than collections of valuable ancient objects. When analysed collectively, they provide evidence of the changing economic relationships connecting Roman territories.
First Came the Army
The Roman army inevitably occupies a central place in the story.
Legions required food, animals, equipment, weapons, clothing and enormous logistical systems.
Soldiers also needed to be compensated.
Where armies travelled, economic activity followed.
A traditional interpretation therefore sees military expansion as one of the principal mechanisms through which Roman money spread.
The new analysis does not reject that interpretation.
Instead, it refines it.
Military structures appear to have been particularly important during the initial stages of expansion.
The arrival of Roman forces stimulated monetary activity in recently conquered territories.
But something changed once conquest became permanent rule.
Then Came the Economy
As territories became incorporated into Roman political structures, the relative influence of military expenditure declined.
Civilian mechanisms became increasingly important.
Markets developed.
Administrative institutions operated.
Cities became more deeply connected.
Religious and civic structures contributed to permanent settlement and institutional life.
Commercial networks intensified.
The crucial finding is therefore that military power could initiate monetary circulation without being sufficient to sustain it indefinitely.
Permanent economic integration required institutions and continuing demand for currency.
This provides a valuable way of thinking about Roman imperial expansion.
A legion could defeat an opposing army.
It could occupy a city.
It could impose Roman authority.
But transforming conquered territory into an enduring component of the Roman system required considerably more.
The Shrinking Importance of Distance
Perhaps the study’s most revealing result concerns geographical distance.
During earlier periods, coins tended to remain comparatively close to their places of minting.
As Roman territorial expansion continued, researchers increasingly found coins farther from their origins.
In the statistical models, the restrictive effect of distance gradually declined.
Regions previously separated by geography became increasingly connected through transportation infrastructure, markets and institutions.
This is an important economic signal.
In poorly integrated economies, distance imposes enormous costs.
Transport is difficult.
Information travels slowly.
Markets remain local.
Different regions can function relatively independently.
As infrastructure improves and institutions become more interconnected, distance becomes less economically restrictive.
The Roman evidence appears to capture precisely such a process.
Roads Were Economic Infrastructure
Roman roads are among the civilisation’s most famous physical remains.
They are frequently discussed primarily in military terms.
Roads allowed legions to move rapidly, supplied frontier positions and helped the state respond to rebellions or external threats.
But their economic significance was equally profound.
Transport infrastructure reduced some of the barriers separating communities.
Goods could move.
Officials could travel.
Messages could circulate.
Taxes and payments could be transferred.
Markets could become connected.
The coin evidence reinforces the idea that Roman infrastructure helped transform military geography into economic geography.
Ports played a similar role.
The Mediterranean itself connected distant regions through maritime commerce, allowing some goods to travel distances that would have been prohibitively expensive by land.
Different Roman Economic Zones
The analysis also identified different functional geographical areas within the expanding Roman system.
At the centre stood Rome itself, where public administration represented a particularly important component of expenditure.
Beyond the capital was the Italian Peninsula, forming a comparatively mature and highly integrated economic core in which market activity played a larger role.
Farther outward lay what the researchers describe as an intermediate or buffer zone.
Here military, administrative and economic expenditures overlapped.
At the edges of recent expansion, expenditure associated with conquest and occupation remained more important.
The pattern changed as territories became consolidated.
Military spending declined in relative importance.
Civil administration and commercial activity expanded.
This effectively provides an archaeological model of Romanisation viewed through economic networks rather than simply language, architecture or political institutions.
Conquest Was a Process, Not an Event
The findings challenge simplistic maps of Roman expansion.
Historical atlases often represent conquest by changing the colour of a territory after a particular battle or campaign.
Reality was considerably more complicated.
Military victory might establish nominal Roman authority, but genuine integration could take generations.
Infrastructure had to develop.
Administrative systems had to operate.
Local elites had to interact with Roman institutions.
Commercial relationships had to emerge.
Cities and markets had to connect with wider networks.
Money provides one means of observing that process.
A territory might become Roman politically before becoming fully integrated economically.
Coins as Economic Footprints
The study’s title, Economic footprints, captures the underlying idea.
Coins physically move because people move them.
A coin minted in one location but discovered hundreds of kilometres away implies a sequence of human interactions.
Perhaps a soldier carried it.
Perhaps a merchant received it.
Perhaps it was used to purchase grain.
Perhaps it moved through taxation.
Perhaps it changed hands repeatedly before finally being buried or lost.
The precise biography of an individual coin is usually unknowable.
But millions of such movements produce patterns.
Those patterns can be analysed statistically.
In that sense, archaeological coinage becomes a surviving footprint of economic behaviour.
The Limits of the Evidence
There are important reasons for caution.
Archaeological coin distributions do not provide a perfect map of the ancient money supply.
What survives depends on what was lost, deliberately buried, preserved, discovered, excavated, recorded and eventually digitised.
Coin hoards themselves can reflect unusual circumstances.
People may hide money during periods of insecurity and never return to recover it.
Different regions have also experienced radically different histories of archaeological investigation.
The researchers addressed such problems through data curation and by analysing aggregated archaeological records rather than treating every surviving coin as an unbiased observation of ancient economic behaviour.
The conclusions should therefore be understood as reconstructed patterns rather than a complete census of Roman economic activity.
Why Hoards Matter
The wider field of Roman numismatics illustrates the enormous potential of these datasets.
The Ashmolean Museum’s Coin Hoards of the Roman Empire project currently documents around 19,000 hoards containing more than seven million coins, with the broader objective of using numismatic evidence to improve understanding of Roman coin supply, circulation and economic life.
A hoard does not necessarily mean a chest filled with treasure.
Researchers use the term broadly for groups of coins apparently deposited together. These assemblages can reveal which currencies circulated simultaneously within particular places and periods.
Digitisation allows information from thousands of such discoveries to be studied as parts of one enormous archaeological system.
A New Kind of Ancient History
Perhaps the broader significance of the research lies in methodology.
This is history being investigated partly through techniques developed for understanding modern economies.
Geographic information systems reconstruct space.
Transport models estimate connectivity.
Regional economics examines flows.
Statistical methods test whether apparent patterns are meaningful.
Archaeological databases supply millions of observations.
Historical scholarship provides the institutional context necessary to interpret them.
None replaces traditional historical research.
Instead, they create another category of evidence.
Ancient societies that left no spreadsheets, economic surveys or national accounts can increasingly be examined through the enormous material datasets they unintentionally left behind.
Rome’s Real Achievement
Roman military success remains impossible to separate from the Republic’s rise.
Rome defeated Carthage.
Its armies conquered the Hellenistic kingdoms.
Legions moved into Hispania, Gaul and the Balkans.
Military force created the geographical foundations of Roman power.
But conquest alone does not fully explain why Rome endured.
The new research suggests that Roman power became more durable as conquered territories entered interconnected systems of exchange, administration, transportation and monetary circulation.
Rome did not merely occupy territory.
It increasingly connected it.
And once those connections became economically useful, integration could develop beyond the immediate presence of the army.
Four Million Small Pieces of History
A Roman coin is a remarkably small historical object.
Its imagery can reveal political messages.
Its inscription can identify authorities.
Its metal can reveal monetary policy.
Its archaeological location can document movement.
But the greatest revelation may emerge when individual coins stop being studied solely as individual artefacts.
Approximately four million archaeological traces, analysed together, reveal something no single denarius ever could.
They show an economic landscape taking shape.
At first, money followed armies and remained relatively constrained by distance.
Then networks thickened.
Roads and ports connected regions.
Markets expanded.
Administrative institutions became established.
Currency travelled farther.
The economic importance of geographical distance weakened.
Military frontiers gradually became integrated territories.
Rome’s expansion was therefore not simply a succession of victories.
It was the construction of a system.
And two thousand years later, millions of coins scattered beneath the landscapes of Europe and the Mediterranean are allowing historians to reconstruct how that system worked.
Source study: Economic footprints: mapping coin circulation and economic networks in ancient Rome, published in Humanities and Social Sciences Communications, 9 June 2026. The research was conducted by Eduardo Amaral Haddad and Inácio Fernandes Araújo at the University of São Paulo.