Solution
The barter system, in which products were exchanged directly, was the first form of trade in primitive cultures. Prior to the invention of paper and coin currency, rare things of great intrinsic value, such as flintstones, obsidian, cowrie shells, timer's paws, whale's teeth, dogs' teeth, skins, furs, cattle, rice, peppercorns, salt, small tools, copper, silver, and gold, were used to exchange commodities.