It was 1,700 years before the introduction of the Euro that a single currency was being used across the Roman Empire. The numis coins were recognised and used by merchants in Constantinople and citizens of the Eternal City to soldiers stationed on Hadrian’s Wall.
So, in January 2002 when seventeen European nations formally adopted the Euro after scrapping their own currencies, a single currency was not something new. The purpose of the Euro was to simplify trade across the European continent. Under the Romans, the coin was used as part of the Roman conquest, not for conquest sake, but to help subsidize the Empire and their bartering system and to standardise taxation. The value of the coins was based on government decree and not on the value of the content used in the creation of the coinage. This lead to a very high number of coins being minted and inflation was inevitable when too many coins entered the system.
Diocletian’s tried to deal with the inflation by introducing price controls when things got a bit out of hand, which sadly failed, but his introduction of coin denominations, helped to streamline the system as much as possible.
As with the Euro, the Roman coinage had a standardised design on one side and some kind of representation of the country the coins came from on the other.
The Roman single currency was used for centuries, and the Euro has only, to date, been in circulation of just over a decade. The main reason for this is that only one government, the Roman Empire, controlled the Roman single currency. Today the situation is much more complex as more governments are involved in the management of this financial concept that is, as it was in Rome, tightly linked to politics and global economics.
In 400AD the Roman Empire started to crumble. The Romans retreated from across the Continent and took with them their coinage. This was devastating for the British economy. The currency did not just collapse, it was completely removed from Britain. No money meant no trade. It was the biggest financial disaster Britain had ever, and probably ever will, be a victim of. People abandoned the cities and the whole country became vulnerable to invasion from all angles.
This ushered in a period of instability and darkness which later became known as The Dark Ages.