According to UNRV History, the Roman economy came up with the idea to use Aes Rude, which means raw bronze, as a type of bartering system to make the exchange of goods easier. These coins were not only used for the exchange of goods but also for the manufacturing of other objects when they were melted down in adequate quantities.
UNRV History says that Aes Rude was replaced sometime around 300 B.C. by Aes Signatum, which means signed bronze. The change was made because the circulation of Aes Rude was becoming common, and the Roman Empire saw a chance to further improve its bartering system. Unlike the Aes Rude, Aes Signatum were all the same weight and shape. This means that vendors no longer had to weigh coins when bartering, which increased the speed of transactions. These coins were also cast with marks that bore the government authority.
Unfortunately, Aes Signatum was heavy to carry around in large quantities at nearly 1,600 grams a piece, according to UNRV History. Aes Signatum was quickly replaced by Aes Grave, meaning heavy bronze, around 269 B.C. Aes Grave was the first Roman coin available in several denominations. The different denominations were marked by animals and gods.