Nowadays, one who writes the history of a field of knowledge is confronted with two methodological injunctions that invite him to cross boundaries: globality and interdisciplinarity. This is particularly true if this knowledge is still being practiced, if its history is long and if it has widely circulated in space and across disciplines, as is the case with philosophy. At the turn of the nineteenth century, the historicization of learned practices accompanied their disciplinary institutionalization in universities. The history of philosophy had the function of legitimizing disciplinary practices by connecting them to a long-standing tradition, or by challenging the tradition to mark a new beginning. In both cases, these uses of the past gave rise to various methodological problems. This paper summarizes them under three key words: anachronism, periodization and definition. It then presents a recent project to overcome the disciplinary aporias of historicism: the history of knowledge. Finally, it asks what the benefit would be of immersing the history of philosophy in the history and anthropology of knowledge. As exemplary issues, it addresses two «savage» continents of philosophical historiography: the Middle Ages and the United States in the nineteenth century.