The earliest coins in the world were minted in the kingdom of Lydia in Asia Minor around 600 BC. The coins of Lydia were made of electrum, which is a naturally occurring alloy of gold and silver, that was available within the territory of Lydia. The concept of coinage, i.e. stamped lumps of metal of a specified weight, quickly spread to adjacent regions, such as Aegina. In these neighboring regions, inhabited by Greeks, coins were mostly made of silver. As Greek merchants traded with Greek communities (colonies) throughout the Mediterranean Sea, the Greek coinage concept soon spread through trade to the entire Mediterranean region. These early Greek silver coins were denominated in staters or drachmas and its fractions (obols).
More or less simultaneously with the development of the Lydian and Greek coinages, a coinage system was developed independently in China. The Chinese coins, however, were a different concept and they were made of bronze.
In the Mediterranean region, the silver and other precious metal coins were later supplemented with local bronze coinages, that served as small change, useful for transactions where small sums were involved.
The coins of the Greeks were issued by a great number of city-states, and each coin carried an indication of its place of origin. The coinage systems were not entirely the same from one place to another. However, the so-called Attic standard, Corinthian standard, Aiginetic standard, and other standards defined the proper weight of each coin. Each of these standards was used in multiple places throughout the Mediterranean region.
In the 4th century BC, the Kingdom of Macedonia came to dominate the Greek world. The most powerful of their kings, Alexander the Great eventually launched an attack on the Kingdom of Persia, defeating and conquering it. Alexander’s Empire fell apart after his death in 323 BC, and the eastern Mediterranean region and western Asia (previously Persian territory) were divided into a small number of kingdoms, replacing the city-state as the principal unit of the Greek government. Greek coins were now issued by kings, and only to a lesser extent by cities. Greek rulers were now minting coins as far away as Egypt and central Asia. The tetradrachm (four drachms) was a popular coin throughout the region Rare Metal Blog. This era is referred to as the Hellenistic era.