This Key Theme is concerned with the role of networks of
economic exchange in history. It has to do with the ways in
which people have exchanged ideas and goods, sometimes over
great distances, and how networks have provided the basic
framework on which the present-day world economy has been
Most of us tend to take the world economy for granted. We
jog in shoes made in Indonesia, wear shirts manufactured in
Guatemala, and listen to world music CDs on a Walkman made
in Korea. We consume Colombian coffee, Argentinian beef, Australian
sugar, and Senegalese peanuts without reflecting on the webs
of exchange that brought those products to our local stores.
Most of us think the world economy is a recent creation.
In fact, it has a deeper history than we might imagine.
Ancient networks of commerce connecting the river valley civilizations
of Egypt, Mesopotamia, and the Indus valley gradually linked
with other regional networks, eventually interlocking most
of Afroeurasia. Well before Europe became economically important
on the world scene, China, India, and the Middle East routinely
traded with one another by way of both the Eurasian silk
roads and the maritime routes of the Indian Ocean. American
Indians, Pacific Islanders, and other peoples were also involved
in long-distance trade. European desire to gain direct access
to Asian pepper and spices fueled their voyages of discovery
of the fifteenth and sixteenth centuries.
Older patterns of exchange greatly changed in the aftermath
of these voyages, which involved European conquest and settlement
in the Americas. For the first time in about 12,000 years,
humans established sustained links between the Eastern and
Western Hemispheres, making possible a truly global system
of exchanges. These developments also altered the place of
Europe in the world economy. Spain and Portugal had access
to previously unimaginable quantities of silver just at a
time when the global system of exchange, which was centered
on Asia, began to demand a much greater volume of that commodity.
The history of exchange networks involves at least three
One is the story of how networks became more and more
complex. Over time, exchanges have become cumulatively deeper,
denser, and more intricate, linking more and more people
over greater and greater distances. Exchanges on these networks
has also taken place at greater and greater velocity. The
size of networks has of course been related to the growing
numbers of humans on the planet, which is the subject of
Key Theme 1.
From a second perspective, economic exchange may be viewed
as traffic in all kinds of information. We may think of
all objects of exchange as potentially containing information-about
the origin of a product, the techniques that produced it,
and the uses to which it might be put. 1
Seen in this way, the history of commerce has involved the
exchange of increasingly complex kinds of cultural and material
information, from spear point design to gunpowder technology
to web site data.
Third, economic exchange is linked to expanding webs of
communication. By communication we mean not only physical
transport but also languages, writing systems, and all means
of conveying things or ideas from one group of people to
another. As communication systems have become more stable,
reliable, and widely accepted, they have greatly enhanced
human capacity for collective
learning. In this way they have contributed to both
the exchange and intricacy of information.
Why did humans trade with one another? They did it for many
reasons, but first of all to acquire goods that they could
not easily find locally. The fact that different groups have
lived in diverse ecological zones has encouraged exchange
networks to develop. For example, peoples who lived along
the great bend of the Niger River in West Africa and depended
upon fishing for their livelihood traded with forest-dwellers
to the south, who produced iron goods, and with Saharan peoples
to the north, who mined and sold salt. In China, the Grand
Canal linked the moist, rice-producing regions of the south
with the wheat-producing regions of the drier north.
We may distinguish different methods of exchanging goods.
involves the direct and reciprocal exchange of goods and
services of supposed equal value, for example farmers and
grain for animals. This method was often sufficient for
local trade, but for long-distance exchange it was cumbersome.
On the regional and interregional levels the exchange
of tokens of various sorts facilitated trade. The materials
used depended on the historical circumstances. For example,
cowrie shells were a medium of exchange in West Africa.
Wampum belts were used among Native Americans. In the first
millennium BCE., merchants who moved goods long distances
across Eurasia started using gold and silver as the preferred
method of reckoning accounts. The natural scarcity of these
metals, together with the physical characteristics that
made them "workable" by artisans, suited them well as tokens
of exchange. Here was the origin of money. The earliest
record we have of the use of gold or silver coins in trade
comes from the kingdom of Lydia in Anatolia (modern Turkey)
in the seventh century BCE.
In the history of exchange, individual cities, regions, and
ethnic groups have tended to specialize in providing particular
commodities or manufactured goods. Sometimes states and empires
have sought to take advantage of this situation by controlling
the lines of trade among different cities or groups. At other
times city-states (like Venice and Genoa in Italy or Kilwa
on the East African coast) have traded on their own account.
Groups sharing language and culture have sometimes established
diasporas. These were ethnically linked communities of
merchants who dispersed themselves across wide distances and
who specialized in developing, managing, and profiting from
long-distance trade. The word diaspora means "scattering."
Here are three examples:
The Phoenicians, whose homeland was a cluster of cities
at the eastern end of the Mediterranean, wove together a
trade diaspora in the early first millennium B.C.E. that
extended to the far western end of that sea.
Scatterings of Chinese merchants established themselves
in cities of the Indian Ocean region long before Europeans
arrived there in the fifteenth century.
Networks of French-, English-, and Indian-speaking groups
moved furs from one trading post to another across the northern
regions of North America in the seventeenth and eighteenth
We might think of networks of economic exchange as made up
of three levels nested in one another-local, regional, and
Everyday commodities and products with relatively low
value and high bulk provided the basis of local exchanges
between towns and the agricultural regions around them.
Goods such as grain, dried fish, timber, or iron ore were
relatively cheap to transport if the distances were not
too great. As a general rule, moving bulk goods by water
was cheaper than transporting them along roads or trails.
Regional networks featured the exchange of more costly
products, for example, moving textiles, pottery, or metal
wares between a market town and its farming hinterland or
between one city and another within a region.
Finally, long-distance trade knitted together cities widely
distant from one another to exchange high value, low bulk
commodities like rugs, spices, gold, silk, or fine ceramics.
Over the long term of history up to 1500 CE, the long-distance
networks that united societies of Afroeurasia
tended to become longer, stronger, and denser. In the Americas,
economic networks expanded as well, though mainly within
regions such as Mesoamerica or the Andean highlands. Finally,
it is important to note that until about 1500 Afroeurasian
and American networks of exchange had no sustained contact
with one another. In the sixteenth century, however, all
major regions of the world became interconnected, laying
the basis for a truly global economy.
Ruins of the city of Sijilmasa
on the northern edge of the Sahara Desert in southern
This city, founded as early as the ninth century CE,
was an important commercial town and a staging center
camel caravans crossing the desert to West Africa. The
journey from Sijilmasa to the Niger River in today's
Mali took about three months.
An American buys spices at a market stall
in Erfud, a town
near the ruins of Sijilmasa in southern Morocco.
Economic exchange networks have always faced limits.
One has been the level of technology. The efficiency with
which humans have produced both goods and information has
always been connected to the worth of their technology.
For example, a small group of people might take a day or
more to cut down a big tree with stone axes, but one person
might do the job in a few hours using a steel axe. Advances
in technology made it possible for people to increase their
output of manufactured goods. As that happened, the volume
of commercial exchange over the networks tended to go up
Another limit has been the amount of energy that humans
have been able to tap to increase production and exchange.
The energy that humans could produce with muscle power,
animal traction, wind, flowing water, or the heat of burning
wood was limited. The fossil fuel
revolution of the eighteenth century, however,
allowed humans to burst through that energy ceiling. The
steam engine, for example, gave humans the ability to extract
vast amounts of energy contained in coal, natural gas, and
petroleum. Electrical and, more recently, nuclear power
have had similar consequences. Therefore, production of
goods and information and their exchange round the world
has increased immensely. Even though commerce has always
had ups and downs, that is, phases of expansion and shrinkage,
we can scarcely imagine what the upper limits of the volume
and variety of worldwide exchange might be in the future.
Why Do We Need to Understand This Key Theme?
Throughout most of the past 200,000 years, humans have
lived in small groups that largely fed, clothed, and sheltered
themselves. They traded with neighbors or strangers only
for things they could not produce themselves. Today, by
contrast, self-sufficient societies are almost unknown.
Even the hundreds of millions of families in various parts
of the world that continue to grow food for themselves depend
on market exchanges for many of their needs. In the United
States, only a tiny minority of families produces its own
food. Most of us are dependent on the market for virtually
all our material desires and needs. We also rely more and
more on it for vital, useful, or entertaining information.
Most of the goods and information we consume originate from
producers we will never see or know. Many of them live thousands
of miles away. We will better understand the ever-changing
world economy, and our place in it, if we have knowledge
of its long development.
The things we consume reach us by way of complex systems
of communication and transport that we are scarcely aware
of. As either working teenagers or fully employed adults,
most of us contribute something to this global economy.
We usually do it, however, in narrowly specialized ways,
serving hamburgers, for example, or selling life insurance.
Also, fluctuations in production, finance, and trade in
distant parts of the world may seriously affect our income,
employment chances, and career plans.
How did we become so dependent on the global economy,
and how might that dependence affect the direction of our
lives? Answers to these questions require a world-historical
perspective, not only the "globalizing" developments of
the past few decades but the long-term trends that transformed
trade from a secondary human economic activity to one that
none of us can do without.
Landscape and Closeup Teaching Units that Emphasize
Key Theme 2:
The idea of information networks is discussed in Christopher
Chase-Dunn and Thomas D. Hall, Rise and Demise: Comparing
World Systems (Boulder, CO: Westview Press, 1997).