First we must work on the definition of ancient coins. To me a coin is a piece of metal bearing an imprint of some kind. It should be easily portable. It would have been recognized as having value to those who used it or passed it on to others as an item of value. This value would not just be local but valuable throughout the trading region of the issuing authority. The trade value of the item would not be worth more than the value of the metals contained in the coin. The item was made under the authority of the governing authority in that region. Coins should be basically round or oval semi flat discs.
are many ancient pretenders of coins in many different materials
including but not limited to stone, ivory, porcelain, or glass. Most of
these are now considered as tokens.
The great emerging civilizations in china produced metal items that would meet the criteria I have described as the definition of a coin but produced items in a vast variety of shapes before adopting and issuing round coins.
Lydia in Asia Miner (currently Turkey) is recognized as the first meeting the above criteria. There coins were made in electrum, which is an alloy of about 40 percent gold, in about 600 BC. These coins bear the Lion or part of a lion stamped into what appears to have been a soft, river pebble shaped, piece of metal. These are not glamorous but seemed to circulate widely in the region and are valuable.
Another area which started issuing coins sometime later about 500 BC was Attica, Aegina with their turtle topped coins. These are interesting, affordable, collectable and historical to own. These are 2500 years old and yes you can own one without breaking the bank.
For the most part in spite of what archeologists want to argue ancient coins were made in huge quantities for circulation in large areas. There would have been more than 1,000,000 different coins issued before 1000 AD and the number of individual coins would, manufactured by various means, most likely be in the several billions.
Today in China when a hoard of coins is found its contents are measured in tones of coins not numbers of individual pieces.
Coins being of metal interact with the surrounding air, soil and water and start to degenerate from the day of manufacture except for gold coins. Many coins unearthed by metal detectors have perished to the point of being more curios than collectables.
In many parts of the world the value of the metal used to manufacture the coin in its past is worth more than the collectable value of the coin today so they are simply melted down as metal bullion. This has been true all through the period that coins have been manufactured. Many times old coins were simply over struck or melted down and re-manufactured to make newer coins by a new authority.
When most people talk about ancient coins they are usually referring to coins at least 1000 years old from China, the Greek occupied areas, the Roman occupied areas and the Persian occupied areas.