The region later served as the political and cultural base of the Eastern Iranian Parni people and Arsacid dynasty, rulers of the Parthian Empire (247 BC – 224 AD).

The Sasanian Empire, the last state of pre-Islamic Iran, also held the region and maintained the seven Parthian clans as part of their feudal aristocracy.

[citation needed] Parthia was known as Pahlaw in the Middle Persian sources of the Sasanian period, and Pahla or Fahla by later Islamic authors, but mainly referred to the Parthian region in the West of Iran.

[citation needed] By the early Sasanian period, Parthia was located in the central part of the Iranian plateau, neighboring Pars to the south, Khuzistan to the south-west, Media to the north-west, the Alborz Mountains to the north, Abarshahr to the north-east, and Kirman to the east.

Prior to this, the people of the region seem to have been subjects of the Medes,[4] and 7th century BC Assyrian texts mention a country named Partakka or Partukka (though this "need not have coincided topographically with the later Parthia").

"[9] At the Battle of Gaugamela in 331 BC between the forces of Darius III and those of Alexander the Great, one such Parthian unit was commanded by Phrataphernes, who was at the time Achaemenid governor of Parthia.

"[10] Taking advantage of the uncertain political situation, Andragoras, the Seleucid governor of Parthia, proclaimed his independence and began minting his own coins.

[citation needed] Meanwhile, "a man called Arsaces, of Scythian or Bactrian origin, [was] elected leader of the Parni",[11] an eastern-Iranian peoples from the Tajen/Tajend River valley, south-east of the Caspian Sea.

[12] 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"[11][13] – the Parni invaded[14] Parthia and seized control of Astabene (Astawa), the northern region of that territory, the administrative capital of which was Kabuchan (Kuchan in the vulgate).

In exchange for this support, these families received large tracts of land among the earliest conquered territories adjacent to Parthia, which the Parthian nobility then ruled as provincial rulers.

[citation needed] From about 105 BC onwards, the power and influence of this handful of Parthian noble families was such that they frequently opposed the monarch, and would eventually be a "contributory factor in the downfall" of the dynasty.

Each time, the Arsacid dynasts responded personally, doing so even when there were more severe threats from Seleucids or Romans looming on the western borders of their empire (as was the case for Mithridates I).

But when Artabanus attempted to consolidate his position (at which he was successful in most instances), he failed to do so in the regions where the Parthian provincial rulers held sway.

[18] By the 2nd century AD, the frequent wars with neighboring Rome and with the nomads, and the infighting among the Parthian nobility had weakened the Arsacids to a point where they could no longer defend their subjugated territories.

The empire fractured as vassalaries increasingly claimed independence or were subjugated by others, and the Arsacids were themselves finally vanquished by the Persian Sassanids, a formerly minor vassal from southwestern Iran, in April 224.

[citation needed] Parthia was likely the first region conquered by Ardashir I after his victory over Artabanus IV, showing the importance of the province to the founder of the Sasanian dynasty.

The Parthians did, however, have a thriving oral minstrel-poet culture, to the extent that their word for "minstrel" (gosan) survives to this day in many Iranian languages and especially in Armenian (gusan), on which it exercised heavy (especially lexical and vocabulary) influence.

[22] These professionals were evident in every facet of Parthian daily life, from cradle to grave, and they were entertainers of kings and commoners alike, proclaiming the worthiness of their patrons through association with mythical heroes and rulers.

[citation needed] Nisa (Nissa, Nusay) or Mithradātkert, located on a main trade route, was one of the earliest capitals of the Parthian Empire (c. 250 BC).