the medieval mediterranean 83
and goods and can provide figures and thus some quantification; however, information
remains fragmentary, becoming abundant only from the twelfth century and shedding
more light on long-distance trade than on smaller movements that left no written
records (notarial contracts, tax data, and so on). Above all, it is very uneven in spatial
distribution. Byzantine or Muslims documents, though probably numerous, have not
survived; only documents found in archives of northern Mediterranean trading cities
such as Genoa, Pisa, or Barcelona remain. Given the distortions in the overall picture
that result from this imbalance, we must be careful not to overestimate the role played
by merchants of these Latin Christian cities.
For a dynamic view of medieval Mediterranean exchange, we must be attentive to
changes in the networks throughout the period. Trade was conditioned by economic
complementarities which could, of course, be due to structural and natural condi-
tions. But trade networks were even more subject to changes in production and in
consumer markets. They could also be affected by changes in political dominion, by
conflicts and insecurity (even if wars never completely halted commerce), and espe-
cially by the dynamism of actors who promoted the emergence and consolidation of
new economic centers, playing a leading role in the structuring of the networks.
Finally, in this increasingly interconnected world, events—sometimes very distant—
could lead to major and rapid changes in the configuration and the dynamism of trade
networks, facilitated by the speed of information flow in the merchant world.
A first phase, stretching from late antiquity to the tenth century, was characterized
by the slow reconstruction of maritime trade networks on the ruins of the Roman
Empire. Though trade, as we have seen, did not completely disappear with the Muslim
conquests, the networks were profoundly affected and the volume of trade decreased
in a very depressed economic conjuncture. In particular, the north-south axes that
had strongly structured trade networks in antiquity lost their importance, since nei-
ther Rome nor Constantinople controlled the southern shores of the Mediterranean
any longer. On the other hand, new networks were reconstituted within the Byzantine
or Islamic empires at a rhythm that is not always easy to determine.
Though considerably reduced by the Muslim conquests, the Byzantine Empire
managed to maintain a trade network, mainly centered on the capital of Constantinople,
that spanned the Black Sea and the Aegean and stretched westward to southern Italy
(including Sicily until its conquest by the Muslims of Ifriqiya) and the Adriatic, with
Venice continuing to recognize the sovereignty of the Byzantine emperors (Laiou,
2002). Meanwhile, on the southern shore of the Mediterranean, the Arab conquests
contributed to the unification of a vast economic space previously divided between
the Persian and Greco–Roman Empires. As was the case for Byzantium, the new
political and economic centers were located in the east: first Damascus, then Baghdad.
The political divisions that appeared in the middle of the eighth century, in particular
with the secession of a large part of the Islamic west (al-Andalus, central and western
Maghreb), did not disrupt the unity of this economic and commercial zone. The
reforms of the Umayyad caliph ‘Abd al-Malik (685–705) led to the adoption of a
single monetary system (based on gold dinars and silver dirhams) and to the spread of
Arabic, first imposed as the language of administration, as the language of trade
throughout the Empire. Similarly, between the seventh and the ninth centuries, the
codification of Islamic law permitted a certain unification of commercial norms and
practices. It is not certain that the sea served as a main axis of commerce and