Eons ago, before money was created to serve as a medium of exchange, humans traded goods by bartering for products of similar value.
Bartering was inherently inconvenient because live products such as animals could not be divided into smaller portions so they could more easily be exchanged.
Moreover, many products differed in quality, and buyers and sellers differed in their assessments of value and in their requirements.
To facilitate product sales, several mutually-agreed commodities came into use as mediums for exchange. Over time, these commodities changed
according to perceptions of social value. For example, such diverse items as cattle, beads, salt, shells, feathers, tomahawks, arrowheads, leather,
whale teeth, decorations, and base metals have at one time or another been regarded as common currencies.
Ultimately, silver and gold came to be universally perceived as the most practical common currencies. In addition to being rare and durable,
they could be divided into smaller units without losing their original properties. They were convenient to carry and could also be melted into larger blocks.
Often exquisitely decorated, these two metals have been popular mediums of exchange since pre-history.