Trade exists for many reasons. Due to specialization and division of labor, most people concentrate on a small aspect of production, trading for other products. Trade exists between regions because different regions have a comparative advantage in the production of some tradable commodity, or because different regions' size allows for the benefits of mass production.
Trade originated with the start of communication in prehistoric time. Trading was the main facility of prehistoric people, who bartered goods and services from each other. Peter Watson dates the history of long-distance commerce from circa 150,000 years ago. As such, trade at market prices between locations benefits both locations.
Trade is believed to have taken place throughout much of recorded human history. There is evidence of the exchange of obsidian and flint during the stone age. Materials used for creating jewelry were traded with Egypt since 3000 BCE. Long-range trade routes first appeared in the 3rd millennium BCE, when Sumerians in Mesopotamia traded with the Harappan civilization of the Indus Valley. The Phoenicians were noted sea traders, travelling across the Mediterranean Sea, and as far north as for sources of tin to manufacture bronze. For this purpose they established trade colonies the Greeks called emporia.
From the beginning of Greek civilization until the fall of the Roman empire in the 5th century, a financially lucrative trade brought valuable spice to Europe from the far east, including China. Roman commerce allowed their empire to flourish and endure. Their widespread empire produced a stable and secure transportation network that enabled the shipment of trade goods without fear of significant piracy.
The fall of the Roman empire, and the succeeding Dark Ages brought instability to Western Europe and a near collapse of the trade network. Nevertheless some trade did occur. For instance, Radhanites were a medieval guild or group (the precise meaning of the word is lost to history) of Jewish merchants who traded between the Christians in Europe and the Muslims of the Near East.
From the 8th to the 11th century, the Vikings and Varangians traded as they sailed from and to Scandinavia. Vikings sailed to Western Europe, while Varangians to Russia. The Hanseatic League was an alliance of trading cities that maintained a trade monopoly over most of Northern Europe and the Baltic, between the 13th and 17th centuries.
The ascendancy of free trade was primarily based on national advantage in the mid 19th century. That is, the calculation made was whether it was in any particular country's self-interest to open its borders to imports.
The lack of free trade was considered by many as a principal cause of the depression, and World War II. During the war, in 1944, 44 countries signed the Bretton Woods Agreement, intended to prevent national trade barriers, to avoid depressions. It set up rules and institutions to regulate the international political economy: the International Monetary Fund and the International Bank for Reconstruction and Development (later divided into the World Bank and Bank for International Settlements). These organizations became operational in 1946 after enough countries ratified the agreement. In 1947, 23 countries agreed to the General Agreement on Tariffs and Trade to promote free trade.
