This paper seeks to establish an intellectual context for the periplous of Pseudo-Skylax (probably written in or near Athens in 338 to ca. 337 BC). The unknown author is aware of the work of contemporary natural philosophers, including those in the post-Platonic Academy and those who were to form the Peripatos, especially Aristotle, Theophrastos and Dikaiarchos. Among known writers, Dikaiarchos is most likely to have written the periplous; but the case remains unproven. Doubts are also raised as to the validity of the so-called periplographic genre.