Economic Development and Urban Growth in the High Middle Ages 181For peasants, specialization was a mixed blessing.
Monoculture left them more vulnerable to crop failures
than were the subsistence farmers who grew a little bit
of everything. Some evidence is available that diets de-
teriorated as more and more land was devoted to the
cash crop. But from the standpoint of the European
economy as a whole, specialization improved effi-
ciency. It increased the overall production of commodi-
ties because land was not wasted on unsuitable crops,
and it probably improved their quality as well. It also,
by definition, created the basis for a trade in bulk agri-
cultural commodities that grew into a full-blown com-
mercial revolution.
The Commercial Revolution
In the early Middle Ages most trading was local and
conducted through barter. With the growth of agricul-
tural specialization, this form of commerce expanded
without changing its essential principles. Villagers
brought their surplus goods to weekly markets held in a
nearby town and exchanged them for clothing, tools,
or agricultural products that they could not produce ef-
ficiently themselves. Larger transactions were con-ducted at great annual fairs, such as the one at Cham-
pagne that attracted merchants from all over Europe
until well into modern times.
At first, long-distance commerce was largely in the
hands of Jews. Though Jews were not invariably barred
from holding land, Christian hostility kept them so-
cially peripheral and reinforced the natural cosmopoli-
tanism of a people in exile. Their wide-ranging
contacts, reinforced by strong kinship ties, gave them a
powerful advantage when virtually everyone else was
bound by interest and circumstance to the locality of
their birth. This situation began to change in the
eleventh century. The increased volume, safety, and
profitability of trade began to make it more attractive
to Christian entrepreneurs who were able to squeeze
out their Jewish competitors by securing favored treat-
ment from Christian authorities. The anti-Semitic per-
secutions that began in the twelfth century arose
primarily from the crusading impulse, but they coin-
cided with a perceived decline in the economic useful-
ness of the Jews.
The most aggressive of the new traders were the
inhabitants of the Italian coastal towns. By the begin-
ning of the eleventh century, a number of Italian cities
had outgrown their local food supplies and emerged as
net importers of agricultural commodities. Grain, oil,
and other commodities had to be purchased abroad,
usually in Spain or Sicily. Ports such as Pisa, Amalfi, and
Genoa possessed the maritime skills necessary for this
trade and were often forced to engage in it for their
own survival. Only the threat of Muslim piracy stood in
their way. By combining their fleets and taking advan-
tage of political disorder in North Africa, the three
cities were able to drive the Muslims from their bases in
Sardinia, Corsica, and the Balearic Islands by 1088.
Venice, the greatest trading city of them all, had no
contado or agricultural land of its own. It produced little
more than glass and sea salt, but being located at the
head of the Adriatic, it was the perfect center for trade
between the eastern Mediterranean and central Europe.
Dependent upon commerce almost from its beginnings,
Venice, like other Italian ports, owed its eventual suc-
cess to sheer necessity, maritime skill, and location. By
the beginning of the twelfth century, the Italians were
dominant in the Mediterranean carrying trade and were
beginning to extend their routes northward.
The Crusades expanded Italian trade and greatly
increased its value. Those crusaders who wished to go
to the Holy Land by sea went for the most part in Ital-
ian ships and paid dearly for the privilege. When they
arrived, they found a civilization that was in many
ways more sophisticated than their own. They quicklyThe following range of grain yields is taken from harvest
records on the estates of the bishops of Winchester (En-
gland) between 1209 and 1349, a relatively fertile area
that enjoyed good management. The figures are there-
fore probably higher than those for medieval Europe as a
whole, but far below what can be achieved with modern
technology. Yields of wheat on similar lands today have
been known to reach seventy to eighty bushels per acre.
The difference goes far to explain the insufficiency of
medieval diets.
Yield in grains Yield in bushels
per grain planted per acre
Grain Maximum Minimum Maximum Minimum
Barley 5.6 2.8 27.6 11.0
Oats 3.4 1.8 16.0 7.5
Wheat 5.3 2.6 13.6 5.8
Source: J. Z. Titow, Winchester Yields(Cambridge: Cambridge University
Press, 1972), p. 14.TABLE 10.2Medieval Grain Yields