Abstract
In the history of studies, this question has been tackled first and foremost by internal criticism of the text (Markwardt, Nöldeke, Christensen, Boyce). For a long time, the focus has been on the Arsacid period, which is said to have witnessed the eruption of oral narratives in aristocratic readings, involving characters who renewed the Avestian stock, and a competition between the great Parthian families; each would have pushed forward a putative ancestor, hero of the wars that had pitted the young empire against the Saka ("Gōdarzian" cycle) or hero of the Saka themselves ("Sistanian" cycle promoted by the Sūrēn family, who in effect assumed the function of tāj-bakhsh attributed to Rostam). We're also now considering a resourcing that occurred in the Middle Sassanid period, perhaps in conjunction with the temporary recovery of Bactria. The Turanians and in particular their king Afrāsiāb offer a fairly faithful, if composite, picture of the masters of Central Asia from the5th to the 7thcentury . Their kingdom doesn't seem any more particularly nomadic than Iran's; they're not complete foreigners, they're genealogically cousins gone wrong.
On the other hand, neither Rostam, nor his father Zāl, nor his descendants appear in the Avesta. Mas'ūdī mentions a specific cycle, the Saghēsarān ("Chiefs of the Saka", a people present since the 1st c. BC in Sistān Sakastān), who would have been introduced into the national legendarium while continuing to pursue an independent career.
