塞琉古二世
Parthia was during this period constantly receiving new waves of Iranian migrants from Central Asia, most notably the Parni led by Arsaces I. Around 245 BC, Andragoras proclaimed his independence from the Seleucid monarch Seleucus II Callinicus (), and made his governorate an independent kingdom. Following the secession of Parthia and Hyrcania from the Seleucid Empire and the resultant loss of Seleucid military support, Andragoras had difficulty in maintaining his borders, and about 238 BC—under the command of Arsaces I, the Parni invaded Parthia and seized control of Astabene (Astawa) from Andragoras, the northern region of that territory, the administrative capital of which was Kuchan. A short while later the Parni seized the rest of Parthia from Andragoras, killing him in the process. Hyrcania was shortly conquered by the Parni as well.