The historian attempting to comprehensively establish the living conditions of a particular society, or to determine rises and falls in population, is setting out on a difficult path. The sources and documents are typically lacking and he is thus forced to 'invent' new sources or use methods borrowed from elsewhere to make the existing sources speak. Indeed, when examining a document, he may be compelled to adopt the approaches of other disciplines such as social anthropology, ethnographic enquiry, or quantitative methodologies. This study – after tracing the development of quantitative history through its various pioneers and schools of thought – looks in depth at methods by which the population of various historical Islamic cities can be measured. These methods draw on demographic theories, ways of teasing out the demographic clues scattered throughout classical texts, and mathematical extrapolations based on the area of and number of public buildings in these cities that can be used as indicators of population dynamics.