The contention that the scene depicts the festival for Athena is fraught with problems. Later sources indicate that a number of classes of individual who performed a role in the procession are not present in the frieze, these include: the hoplites, the allies in the Delian League, the "skiaphoroi" or umbrella bearers, the female "hydraiphoroi" (only male hydrai bearers are portrayed), the "thetes", slaves, metics, the Panathenaic ship, and some would suggest the "kanephoros", although there is evidence that she is accounted for. That what we now see was meant to be a generic image of the religious festival is problematic since no other temple sculpture depicts a contemporary event involving mortals. Locating the scene in mythical or historical time has been the principal difficulty of the line of inquiry. John Boardman has suggested that the cavalry portray the heroization of the "Marathonomachoi", the hoplites who fell at Marathon in 490, and that, therefore these riders were the Athenians who took part in the last pre-war Greater Panathenaia. In support, he points out the number of horsemen, chariot passengers (but not charioteers), grooms, and marshals comes to the same as the number Herodotos gives for the Athenian dead: 192. Equally suggestive of a reference to the Persian Wars is the similarity several scholars have noted of the frieze to the Apadana sculpture in Persepolis. This has variously been posited to be democratic Athens counter-posing itself to oriental tyranny, or, aristocratic Athens emulating the Imperial East. Further to this zeitgeist argument there is J.J. Politt’s contention that the frieze embodies a Periclean manifesto, which favours the cultural institutions of "agones" (or contests, as witnessed by the "apobatai"), sacrifices, and military training as well as a number of other democratic virtues. More recent scholarship pursuing this vein has made the frieze a site of ideological tension between the elite and the "demos" with perhaps, only the aristocracy present, and merely veiled reference to the ten tribes.