Monetary system of the Roman Empire

Two millennia before the introduction of the Euro, almost the whole of Europe, North Africa, and a major part of Asia were united in a single monetary system as integral parts of the Roman empire. This system was a continuation of the one that existed in the Roman Republic and was based on coins made of gold, silver, and different copper-based alloys. In the early years of the Roman Empire, the rule of emperor Augustus, the basic Roman denominations were the aureus (gold, 8 grams), denarius (silver, 4 grams), sestertius (brass, 27 grams), and as (copper or bronze, 10 grams). They were exchanged in the ration 1 aureus = 25 denarii = 100 sestertii = 400 assēs.  The Roman monetary system remained stable for several centuries in spite of the fact that economic and political crises often led to inflation and the shortage of precious metals which resulted in the reduction in the metal purity of coins and their weight. The first emperor to introduce such measures was Nero in AD 64. This process was accelerated significantly after the death of the emperor Commodus and the entry into the period of the civil war crisis at the end of the second century. In an attempt to reign in inflation and to pay his troops, in AD 215 emperor Caracalla introduced a new silver coin named after him, antoninianus. In theory it had to be exchanged for two denarii but in reality it weighed only 50 % more than a denarius. The silver content in the antoninianus fell from 50 % in AD 215 to less than 3 % in AD 272, when these coins were actually only coated with a silver layer. This led to the disappearance of the denarius from circulation. The aureus also lost a lot of its weight and in the period of the soldier emperors, after the middle of the third century, which is the subject of this book, fell to less than 4 grams.

The chaos in the Roman monetary system was addressed by the reform of the emperor Diocletianus, who in AD 301 introduced new coin denominations and stricter standards for their weight and metal purity.

It must be noted that in the Eastern Roman provinces the local administrators struck coins in the names of their cities which legally circulated together with the official centrally issued coins. These coins were based on the Greek monetary systems with the drachm as the main denomination and were usually with inscriptions in Greek, which remained the primary language in these areas.