Figures leading or riding horses, a subject that had been popular on early black-figure vases, became significant again during the second half of the fifth century B.C. The major reason lies in the sculptural decoration of the Parthenon, which was executed between about 448 and 432 B.C. and exerted a profound influence on artists working in all media. While equestrian motifs are prominent throughout the program, the riders who make up the western end of the Parthenon frieze surely inspired the painter of this vase.
Richter, Gisela M. A. 1925. "Athenian Red-Figured Vases." Bulletin of the Metropolitan Museum of Art, 20(5): p. 132.