In c. 250 BC, Arsaces and his Parni followers seized Astauene, which lay near the Atrek valley. A few years later, probably in c. 247 BC, Arsaces was crowned king in Asaak, a city which he had founded, and which served as the Arsacid royal necropolis. His coronation at Asaak is generally presumed to mark the start of the Arsacid dynasty. Around 245 BC, Andragoras, the governor of the Seleucid province of Parthia, proclaimed his independence from the Seleucid monarch Seleucus II Callinicus (), and made his governorate an independent kingdom. Following the secession of Parthia 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 and his brother Tiridates 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.