Metallic money first circulated in the form of rings and bars. The Egyptians had small pieces of gold--"cow gold"--each of which was simply the value of a full-grown cow. [3] It was necessary to weigh the metal whenever a purchase took place. A common picture on the Egyptian monuments is that of the weigher with his balance and scales. Then the practice arose of stamping each piece of money with its true value and weight. The next step was coinage proper, where the government guarantees, not only the weight, but also the genuineness of the metal. [Illustration: EGYPTIAN WEIGHING "COW GOLD"] COINAGE The honor of the invention of coinage is generally given to the Lydians, whose country was well supplied with the precious metals. As early as the eighth century B.C. the Lydian monarchs began to strike coins of electrum, a natural alloy of gold and silver. The famous Croesus,[4] whose name is still a synonym for riches, was the first to issue coins of pure gold and silver. The Greek neighbors of Lydia quickly adopted the art of coinage and so introduced it into Europe. [5] BANKING The use of money as a medium of exchange led naturally to a system of banking. In Babylonia, for instance, the bankers formed an important and influential class. One great banking house, established at Babylon before the age of Sennacherib, carried on operations for several centuries. Hundreds of legal documents belonging to this firm have been discovered in the huge earthenware jars which served as safes. The Babylonian temples also received money on deposit and loaned it out again, as do our modern banks. Knowledge of the principles of banking passed from Babylonia to Greece and thence to ancient Italy and Rome. 15. COMMERCE AND TRADE ROUTES ASIATIC COMMERCE The use of the precious metals as money greatly aided the exchange of commodities between different countries. The cities of the Tigris- Euphrates valley were admirably situated for commerce, both by sea and land. They enjoyed a central position between eastern and western Asia. The shortest way by water from India skirted the southern coast of Iran and, passing up the Persian Gulf, gained the valley of the two great rivers. Even more important were the overland roads from China and India which met at Babylon and Nineveh. Along these routes traveled long lines of caravans laden with the products of the distant East--gold and ivory, jewels and silks, tapestries, spices, and fine woods. Still other avenues of commerce radiated to the west and entered Asia Minor, Syria, and Egypt. Many of these trade routes are in use even to-day. [Illustration: Map, ANCIENT TRADE ROUTES] COMMERCE WITH EUROPE