Direct barter of the thing you produce for the thing they produce is of course difficult and inefficient. But barter in pre monetary cultures often involved th

Direct barter of the thing you produce for the thing they produce is of course difficult and inefficient. But barter in pre monetary cultures often involved the exchange of a third commodity that was commonly traded - things like salt, spices, alcohol, oil, copper and silver. Things that were in high demand and were non-perishable. Coins developed as standardised units of the precious metals that were already being exchanged.