One of the great economic improvements of the ancient age was the development of money, which first appeared in Greek Asia Minor as coins made of electrum, a natural alloy of gold and silver. Money acted as a medium of exchange, a storehouse of value, and a standard of value, all of which greatly increased the efficiency of commerce. Without money, all trade was barter, which is greatly inefficient due to the time needed to reach agreement on fair rates of exchange for widely diverse commodities.