Bullion and ingots of various metals were used as currency as early as 5,000 B.C. It’s the Lydians, hailing from an area between the Mediterranean and Asia in the 7th century B.C., who are credited as the first European culture to use money. It’s a pretty safe bet that the Romans knew about the concept of coin-as-money long before they implemented the system in the 3rd century B.C., too.
Bartering cattle for goods or services was the most common method of exchange when the Roman Republic was founded. In fact, many experts say that the Romans didn’t really have a need for a coin-based currency. But because their neighbors had been using coins for centuries, the Romans established the system as a way to keep up.
The earliest bronze bits were marked to indicate weight and worth. The Romans then introduced silver into the coinage. In about 211 B.C. the Romans overhauled their system and the silver dēnārius was minted. It was lighter and worth more than the original and quickly became the basis for the Roman system. From that point on, silver became more widely used than bronze.
Still, it cannot be said that there was much uniformity. In 84 B.C., and again in 45 B.C., coins were minted with the express purpose of paying soldiers at the end of the war. These were noticeably different than the ones minted just decades prior. Others were produced when control of the empire was in an imbalance or when more money was needed. This constant change lasted until the beginning of Rome’s Imperial Age (roughly 3-4 A.D.), when Augustus instituted a reformation that endured three centuries. His various monies were denoted not just by name, but by composition of silver, bronze, copper, gold and brass. Confusion ensued as any number of different coins may have been found. The Barbarians’ invasions in the 3rd century put an end to that, causing a collapse of the growing problem.
Reforms began to ensure more uniformity. Starting with Julius Caesar the emperor’s likeness was stamped onto all new coins, pulling double-duty by providing both monetary value and public relations help. Often, the only time citizens knew they were under a different ruler was when they saw a new face on a coin.