Before there was coinage with faces on it, people used chunks of metal (called hacksilber) to trade. This process was determined by weights and a scale. Standardized coinage and weights are a rather new invention; both ancient coinage and the weights often were reduced as eras shifted and changed - and as precious metal was being used more often. The demand often couldn't keep up with supply.
Initially, faces or symbols on coins were used as a political statement - as there wasn't really a way to communicate who ruled you at any given time. It often took many years for this information to get passed down to all the small isolated towns and villages.
Although they can be hard to come by - by today's standards at least, hacksilber was the origin of all coinage. Here are some from my collection.