Although several sources (e.g. al-Biruni) appear to have considered 'Arash' to be the origin of the name 'Arshak' (i.e. Arsaces), the name of the Parthian dynasty derives from a Parthian- or Eastern Iranian equivalent of 'Ardashir', i.e. 'Artaxerxes', specifically Artaxerxes II, who the Arsacids claimed to descend from.
Nasr, Seyyed Hossein (1993), An Introduction to Islamic Cosmological Doctrines: Conceptions of Nature and Methods Used for Its Study by the Ikhwan Al-Safa, Al-Biruni, and Ibn Sina, State University of New York Press
Apart from Ferdowsi, Rumi, Abu Ali Sina, Al-Biruni, Unsuri Balkhi, Farrukhi Sistani, Sanayi Ghaznawi and Abu Sahl Testari were among the great Iranian polymaths and poets of the period, supported by the Ghazanavids.