Parthyaea

Further west, between Bactria and the eastern shore of the Caspian Sea, Parthyaea, a vast region corresponding to the northeast of Iran, was invaded by a nomadic population under a chief named Arsaces.

He was replaced by Phrataphernes in Parthyaea before 329 (3. 28. 2); and Hyrcania could then have been annexed and associated as a separate satrapy with the Elburz peoples, all under Autophradates.