Early Trade - The discovery of nonlocal objects at many archaeological sites strongly suggests that trade existed in prehistoric times. Anthropologists and other explorers have found trade institutions among diverse peoples throughout the world. The ceremonially elaborate kula trade ring of the Trobriand Islands, the gift-giving potlatch of W Canada's Kwakiutl , and the desert caravan of N Africa and the Arabian peninsula are among the more famous examples. In the Western world a number of peoples, including the Egyptians, Sumerians, Cretans, Phoenicians, and Greeks, at one time or another dominated trade. The Crusades did much to widen European trade horizons and prefaced the passing of trade superiority from Constantinople to Venice and other cities of N Italy.
The theory of commerce as imposed by the national state has varied from the mercantilism of the 17th and 18th cents. and the protective tariff of the 19th and 20th cents. to the free trade that Britain long upheld. Since World War II a realization of the need for commercial expansion has led to the creation of regional trade zones, the prime example being that of the European Union . A trade agreement among the United States, Canada, and Mexico, called the North American Free Trade Agreement (NAFTA), was signed in 1992, and in 2001 34 nations committed themselves to the development of a free trade area encompassing the Western Hemisphere.