It is believed that stimulus leading to the creating and spreading of exchange trade was the moment when man started producing more agricultural crops than they can consume. The excess was then exchanged for things they were interested in with others.
This type of trade had one major disadvantage – the lack of a universal value indicator of exchanged products. It was a serious disadvantage as it was not always possible to find purchasers for products and he did not always have something interesting to exchange.
Food – one of the most often exchanged goods – petrified very quickly so what wasn’t exchanged, was wasted. In the course of time the disadvantage became so serious that it was necessary to use a universal value indicator of all objects – strictly speaking money.
In the second half of the 3rd millennium BC exchange trade was replaced with the first system considered to be the beginning of money exchange. Then metal bullions (usually silver) started to be used and were cut into smaller pieces to be used as money in the earliest form.
Phoenicians started stamping parts of metal that were previously weighed, determining their worth. Later instead of stamping shapeless parts they started to smelt balls, which after stamping they flattened to become the first coins. The oldest round coins came from 650 BC from Sardes in Asia Minor.
The value of coins was based on content of particular metal in it (silver, gold or copper in the ancient times)and that enabled gradual depreciation because some rulers “spoiled” them (i.e. stamping bigger value then it was actually worth or making the coin thinner in order to create more coins).
Eventually, the fall of Rome caused chaos in all monetary system.