A、The isolated peoples mainly use coins and paper money as the medium of exchange. B、The isolated peoples often engage in busine

Aristotle, file Greek philosopher, summed up the four chief qualifies of money some 2,000 years ago. It must be lasting and easy to recognize, to divide, and to carry about. In other words it must be, "durable, distinct, divisible and portable". When we think of money today, we picture it either as round, flat pieces of metal which we call coins, or as printed paper notes. But there are still parts of the world today where coins and notes are of no use. They will buy nothing, and a traveler might starve if he had none of the particular local money to exchange for food.
    Among isolated peoples, who are not often reached by traders from outside, commerce usually means barter. There is a direct exchange of goods. Perhaps it is fish for vegetables, meat for grain, or various kinds of food in exchange for pots, baskets, or other manufactured goods. For this kind of simple trading money is not needed, but there is often something that everyone wants and everybody can use, such as salt to flavor food, shells for ornaments. These things--salt, shells or metals --are still used as money in out-of-the-way parts of the world today.