that language. Arsacid Pahlavi Following the overthrow of the Seleucids, the Parthian Arsacids—who considered themselves the legitimate heirs of the Achaemenids—adopted the manner, customs and government of the Persian court of two centuries previously. Among the many practices so adopted was the use of the Aramaic language ("Imperial Aramaic") that together with Aramaic script served as the language of the chancellery. By the end of the Arsacid era, the written Aramaic words had come to be understood as logograms, as explained above. The use of Pahlavi gained popularity following its adoption as the language/script of the commentaries (Zend) on the Avesta. Propagated by the priesthood, who were not only considered to be transmitters of all knowledge but were also instrumental in government, the use of Pahlavi eventually reached all corners of the Parthian Arsacid empire. Arsacid Pahlavi is also called Parthian Pahlavi (or just Parthian), Chaldeo-Pahlavi, or Northwest Pahlavi, the latter reflecting its apparent development from a dialect that was almost identical to that of the Medes. Sasanian Pahlavi Following the defeat of the Parthian Arsacids by the Persian Sasanians (Sassanids), the latter inherited the empire and its institutions, and with it the use of the Aramaic-derived language and script. Like the Parthians before him, Ardeshir, the founder of the second Persian Empire, projected himself as a successor to the regnal traditions of the first, in particular those of Artaxerxes II, whose throne name the new emperor adopted. From a linguistic point of view, there was probably only little disruption. Since the Sassanids had inherited the bureaucracy, in the beginning the affairs of government went on as before, with the use of dictionaries such as the Frahang-i Pahlavig assisting the transition. The royalty themselves came from a priestly tradition (Ardeshir's father and grandfather were both, in addition to being kings, also priests), and as such would have been proficient in the language and script. More importantly, being both Western Middle Iranian languages, Parthian was closely related to the dialect of the southwest (which was more properly called Pārsi, that is, the language of Pārsā, Persia proper). Arsacid Pahlavi did not die out with the Arsacids. It is represented in some bilingual inscriptions alongside the Sassanid Pahlavi; by the parchment manuscripts of Auroman; and by certain Manichaean texts from Turpan. Furthermore, the archaic orthography of Sasanian Pahlavi continued to reflect, in many respects, pronunciations that had been used in Arsacid times