56 Chapter Two
Nor were the seas the only important medium of long-distance
travel. From about the beginning of the Christian era, caravans had
begun to link China with the Middle East and with India. Animal
packtrains moving from oasis to oasis through the desert or semi-
desert country of central Asia resembled ships moving from port to
port. The conditions of successful operation were similar. Protection
rent had to be adjusted by a process of trial and error until an optimal
level at which local rulers and long-distance traders could support one
another most efficiently was discovered.
Such arrangements were perpetually liable to disruption. Plunder
and outright confiscation always tempted local power wielders, and
alternate routes were less easy to find overland than when crossing
open water. Nevertheless, caravan connections between China and
western Asia were never broken off for very long after the first such
ventures achieved success. In the course of the next ten centuries, the
customs and attitudes that allowed the caravan trade to thrive filtered
northward into the steppe and forest zones of Eurasia. Gradually a
north-south exchange of slaves and furs for the goods of civilization
supplemented the east-west flow of goods that initially sustained the
caravans.
To be sure, evidence is scanty and indirect. The main register of
northward penetration of trade patterns is the spread of civilized reli
gions among the oasis and steppe peoples of Asia—Buddhism, Nesto-
rian Christianity, Manicheanism, Judaism, and, most successful of
them all, Islam. Tribute missions dating back to Han times, when
nomad rulers visited the Chinese capital and received “gifts” from the
emperor and gave “gifts” in return, also attest to penetration of the
steppe by a ritualized and heavily politicized form of trade. But for the
most part we do not know very much about how nomads and traders
entered into symbiotic relationships with one another.^66
Yet pastoral nomads found the advantages of trade with civilized
populations very compelling. Apart from the symbolic value of luxury
goods and the practical usefulness of metal for tools and weapons,
both of which assumed great importance in nomad society by or be
fore the tenth century, a nomad population could greatly expand its
food supply by modifying a diet prodigally rich in protein through
trading off some of their animals and animal products for cereals. The
upper classes of civilized societies—and especially those in China
where animal husbandry was poorly developed—were willing to pay
- Luc Kwanten, Imperial Nomads: A History of Central Asia, 500–1500 (Philadel
phia, 1979), conveniently summarizes the current state of knowledge.