Historians venturing to inquire into the specificity of the mountains and its many facets would do well to start by the actors: first the human beings, not the mountains. Only this way can one step back sufficiently from the popular and the scholarly representations, and the prejudices they perpetuate, of mountain societies. Indeed, the specificity is expressed by many manifestations of human existence, and it is subject to the process of historic change. Population density may be seen as a suitable indicator with which to analyse the issue in a particularly clear and systematic manner. The example of the Alps shows that demographic factors had a strong impact on agricultural practices, urban growth and other economic phenomena.But we should also ask to what extent the density approach works in different contexts, and if it can be useful for the study of political phenomena.