This is the first comprehensive analysis of the economic transition from antiquity to the Middle Ages in over sixty years. It brings fresh evidence to bear on the fall of the Roman empire and the origins of the medieval economy. The book uses new material from recent excavations, and develops a new method for the study of hundreds of travelers to reconstitute the communications infrastructure that conveyed those travelers--ship sailings, overland routes--linking Europe to Africa and Asia, from the time of the later Roman empire to the reign of Charlemagne and beyond.