The independent state of Lydia in Asia Minor is credited with the invention of coinage, around 635 BC, although the Greek historian Herodotus claimed that it was Croesus, the 6th century king of Lydia, who first minted gold and silver coins. Cyrus' conquest of Lydia may have resulted in the introduction of coinage into the Persian Empire but this innovation is usually attributed to Darius.
A 'lion and bull' motif was impressed on these coins. This great monetary innovation revolutionized commerce and older fiscal methods throughout West Asia. Darius had fine gold coins called 'darics' and silver coins called 'sigloi' minted. The king's figure was impressed on these coins, usually in the form of an archer.
Darius' standardization of the value of precious metals in terms of degree of purity, called the 'king's measure', was recognized everywhere and accelerated the use of coinage in the west.
Coinage was used to cover military expenditure and tribute from the provinces was fixed in terms of silver coins. The widespread use of coinage helped facilitate trade in the west, but its circulation in the eastern half of the empire seems to have been minimal.
