In early times foreign trade consisted in the direct exchange of commodities. A caravan set out with a variety of manufactured articles, across the deserts of Arabia or Sahara, and came back with the ivory, spices, and other valuable raw products obtained by barter. In later times the merchant loaded his own ship and sent her forth on an adventure, trusting that his shipmaster would sell the cargo to advantage, and, with the proceeds, bring back another cargo to be sold to great profit at home. Trade was thus reciprocal, and what was sent out paid for what was brought back.

Wherever this direct reciprocal exchange did not exist it was necessary to devise some mode of transferring debts. To the early Italian and Jewish merchants we owe the development of the use of the credit instruments which have since developed into bills of exchange. As early as the fourteenth century bills were used under similar customs and of about the same form as those of the present day.