[12] Its latter name comes from its founder, Arsaces I,[13] who led the Parni tribe in conquering the region of Parthia[14] in Iran's northeast, then a satrapy (province) under Andragoras, who was rebelling against the Seleucid Empire.

Aside from scattered cuneiform tablets, fragmentary ostraca, rock inscriptions, drachma coins, and the chance survival of some parchment documents, much of Parthian history is only known through external sources.

[21] Homa Katouzian[22] and Gene Ralph Garthwaite[23] claim it was the year Arsaces conquered Parthia and expelled the Seleucid authorities, yet Curtis[21] and Maria Brosius[24] state that Andragoras was not overthrown by the Arsacids until 238 BC.

[38] Whereas Hecatompylos had served as the first Parthian capital, Mithridates I established royal residences at Seleucia, Ecbatana, Ctesiphon and his newly founded city, Mithradatkert (Nisa), where the tombs of the Arsacid kings were built and maintained.

[55] Following the Seleucid withdrawal from Mesopotamia, the Parthian governor of Babylonia, Himerus, was ordered by the Arsacid court to conquer Characene, then ruled by Hyspaosines from Charax Spasinu.

[69] A year following Mithridates II's subjugation of Armenia, Lucius Cornelius Sulla, the Roman proconsul of Cilicia, convened with the Parthian diplomat Orobazus at the Euphrates river.

[75] Following the outbreak of the Third Mithridatic War, Mithridates VI of Pontus (r. 119–63 BC), an ally of Tigranes II of Armenia, requested aid from Parthia against Rome, but Sinatruces refused help.

[80] Aulus Gabinius, the Roman proconsul of Syria, marched in support of Mithridates to the Euphrates, but had to turn back to aid Ptolemy XII Auletes (r. 80–58; 55–51 BC) against a rebellion in Egypt.

[85] Surena's 1,000 cataphracts (armed with lances) and 9,000 horse archers were outnumbered roughly four to one by Crassus' army, comprising seven Roman legions and auxiliaries including mounted Gauls and light infantry.

[95] The triumvir Mark Antony was unable to lead the Roman defense against Parthia due to his departure to Italy, where he amassed his forces to confront his rival Octavian and eventually conducted negotiations with him at Brundisium.

[115] During the reign of Artabanus II, two Jewish commoners and brothers, Anilai and Asinai from Nehardea (near modern Fallujah, Iraq),[116] led a revolt against the Parthian governor of Babylonia.

This backfired when Meherdates was betrayed by the governor of Edessa and Izates bar Monobaz of Adiabene; he was captured and sent to Gotarzes, where he was allowed to live after having his ears mutilated, an act that disqualified him from inheriting the throne.

[127] William Watson speculates that the Parthians would have been relieved at the failed efforts by the Han Empire to open diplomatic relations with Rome, especially after Ban Chao's military victories against the Xiongnu in eastern Central Asia.

[139] Whereas Augustus and Nero had chosen a cautious military policy when confronting Parthia, later Roman emperors invaded and attempted to conquer the eastern Fertile Crescent, the heart of the Parthian Empire along the Tigris and Euphrates.

[140] To match Parthia's strength in missile troops and mounted warriors, the Romans at first used foreign allies (especially Nabataeans), but later established a permanent auxilia force to complement their heavy legionary infantry.

[143] The primary motivations for war were the advancement of the personal glory and political position of the emperor, as well as defending Roman honor against perceived slights such as Parthian interference in the affairs of Rome's client states.

Indeed, shortly afterward, Ardashir I, the local Iranian ruler of Persis (modern Fars province, Iran) from Istakhr began subjugating the surrounding territories in defiance of Arsacid rule.

[181] Along with parchment documents found at sites like Dura-Europos, these also provide valuable information on Parthian governmental administration, covering issues such as taxation, military titles, and provincial organization.

123) describes diplomatic exchanges, exotic gifts given by Mithridates II to the Han court, types of agricultural crops grown in Parthia, production of wine using grapes, itinerant merchants, and the size and location of Parthian territory.

[199] The Parthian Empire also contained several subordinate semi-autonomous kingdoms, including the states of Caucasian Iberia, Armenia, Atropatene, Gordyene, Adiabene, Edessa, Hatra, Mesene, Elymais, and Persis.

[201] This was not unlike the earlier Achaemenid Empire, which also had some city-states, and even distant satrapies who were semi-independent but "recognised the supremacy of the king, paid tribute and provided military support", according to Brosius.

[205] Brosius provides an extract from a letter written in Greek by King Artabanus II in 21 AD, which addresses the governor (titled "archon") and citizens of the city of Susa.

[210] Strabo, in his Geographica, preserved a claim by the Greek philosopher and historian Poseidonius that the Council of Parthia consisted of noble kinsmen and magi, two groups from which "the kings were appointed.

For example, when Chinese envoys visited Parthia in the late 2nd century BC, the Shiji maintains that 20,000 horsemen were sent to the eastern borders to serve as escorts for the embassy, although this figure is perhaps an exaggeration.

[218] Due to the cost of their equipment and armor, cataphracts were recruited from among the aristocratic class who, in return for their services, demanded a measure of autonomy at the local level from the Arsacid kings.

According to A. Shahbazi, Arsaces "deliberately diverges from Seleucid coins to emphasize his nationalistic and royal aspirations, and he calls himself Kārny/Karny (Greek: Autocrator), a title already borne by Achaemenid supreme generals, such as Cyrus the Younger.

[237] Moreover, the Arsacids claimed familial descent from Artaxerxes II of Persia (r. 404–358 BC) as a means to bolster their legitimacy in ruling over former Achaemenid territories, i.e. as being "legitimate successors of glorious kings" of ancient Iran.

[257] In portraiture the Parthians favored and emphasized frontality, meaning the person depicted by painting, sculpture, or raised-relief on coins faced the viewer directly instead of showing his or her profile.

This singular state of things seems to have become established in the course of the 1st century A.D.[259]Parthian art, with its distinct use of frontality in portraiture, was lost and abandoned with the profound cultural and political changes brought by the Sasanian Empire.

[279] It is believed that such stories as the romantic tale Vis and Rāmin and epic cycle of the Kayanian dynasty were part of the corpus of oral literature from Parthian times, although compiled much later.