Ammianus Marcellinus' excursus on the Huns and Alans in the thirty‐first and last book of his Res Gestae, in which he creates an image of an enemy that threatens the Roman empire, mainly serves to enhance the suspense in the final part of his narrative. It contains a message to the reigning emperor to defend the borders between barbarism and civilization. The narratological motifs and ideological purposes in the portraiture of foreign peoples, which draw on older Greek as well as Latin ethnographical templates, prevail over historical accuracy. The article addresses the topic from the theoretical framework of alterity, and explores the ethnographical and geographical models on which Ammianus based his largely fictitious account.