Epilogue
The premodern Afro–Eurasian world system was the product of develop-
ments that are best understood by relating them to the basic questions
mentioned in the Preface. First, who and why: exchange began as reciprocal
gift-giving under the control of institutional authorities but over time gave
way to the entrepreneurial, profit-driven activity of private individuals.
Second, what and why: the earliest exchange goods were of the luxury variety
and had some social value attached. This was followed by the earliest mass-
produced goods, which were metals, and the earliest large-scale consumer
goods, which were textiles. Third, how and what: trade was conducted by
land and water evolving from unsystematic trickle trade in the prehistoric
period to directional trade andfinally to grids of exchange that coalesced into
a single whole by thefirst millenniumCE. As the transactions became more
complex, simple barter came to be replaced by the use of mediums of
exchange, that is, money. Andfinally, so what: the impact of long-distance
trade was not just economic; it was a major component in the formation and
development of political and social systems.
For almost a millennium and a half, the Afro–Eurasian trade zone, the
“world system,”maintained its basic structure and systemic integration. It
experienced periods of vigor and regression, but the accompanying changes
did not transform its essential character. The ebbs andflows of the overland
system were determined mostly by considerations relating to security and
stability. On the sea lanes much depended on security but also on improve-
ments in ship construction and navigation techniques. As a result, there was
less change on land than at sea. Underlying shifts in trade were basic con-
siderations involving agricultural productivity, demographic pressures, and
ultimately climatic change. The disruption of trade usually did not impact
equally on all parts of the system. Trade continued so long as the demand
for certain goods held the promise of profits and the basic commercial
infrastructure remained intact.
The period of expansion thatfinally linked Eurasia together was followed
by a period of crisis. Between the third and fifth centuries CE, empires
across the civilized underbelly disintegrated, and people from the nomadic