Book excerpt: The vast resources in the archives of the old trading cities round the Mediterranean have only comparatively recently begun to be fully explored, and they continue to yield new riches. In these studies, which combine the results of such research, in particular in Venice, Genoa, Prato, Ancona and Palermo, with the plentiful data provided by Arabic sources, Professor Ashtor examines the actual mechanics of the Levantine trade, and analyses such crucial problems as the weights and measures used and the changes in prices. He also sets this trade in its broader historical context, both from the point of view of international relations, and as an aspect of Near Eastern history in the period following the Crusades.