The analysis of the so-called “account of the Huns” in the late-fourth-century fundamental history Res Gestae should start from the understanding of the entirety of the source, permeated with the single historiographic concept, where the author’s excursuses form a loose composition, simultaneously playing a role for the author’s goals. The article’s author considers that Ammianus Marcellinus’ goal when describing the nomads in book XXXI of the Res Gestae was to present them as the peoples totally alien to the ancient civilization and as a cause in the chain of events leading to the Roman Empire’s catastrophe at Adrianople in 378 AD. In this regard, the historian did not feel that reliable account of the nomads was necessary. This approach to the account of the Huns was characteristic in this or that way to other late antique writers from Claudius Claudianus and Jerome of Stridon to Zosimus and Jordanes. However, Ammianus was the only one to use a complex of interrelated literary and historical methods to solve the said problem. This complex comprises of hyperbolizing the alienness of the nomads to emphasize the anomaly of their way of life and customs (continuing until they do not have religion nor moral), dehumanizing their physical appearance, and the emphasis on their geographical uncertainty and spatial remoteness from the borders of the Roman Empire. The aim of structure of the “account of the Huns” is to overestimate their wilderness by contrasting them to the Alans, and simultaneously adding to the Hunnic-Alanic alliance the semi-legendary peoples of Scythia, the patterns of which description went back to the age of Herodotus. This technique allows Ammianus to strengthen the impression of the strangeness and danger of the nomadic alliance.