The Italian Renaissance was above all an urban phenomenon, a product of cities
that flourished in central and northern Italy, such as Florence, Ferrara, Milan,
and Venice. It was the wealth of these cities that financed Renaissance cultural
achievements. The cities themselves, however, were not creations of the Renaissance,
but of the period of great economic expansion and population growth during the 12th
and 13th centuries. Medieval Italian merchants developed commercial and financial
techniques, such as bookkeeping and bills of exchange. The creation of the public
debt, a concept unknown in ancient times, allowed these cities to finance their
territorial expansion through military conquest. Their merchants controlled commerce
and finance across Europe. This fluid mercantile society contrasted sharply with the
rural, tradition-bound society of medieval Europe; it was less hierarchical and more
concerned with secular objectives.