Arsaces I and the Founding of the Parthian Empire

Arsaces I was the chief of the Parni, a semi-nomadic people of the Central Asian steppe, who in the mid-3rd century BC seized the Seleucid province of Parthia, south-east of the Caspian Sea. The Parthians later dated their own era from 247 BC, and the dynasty he founded, the Arsacids, ruled Iran and Mesopotamia until AD 224. From a frontier raid grew an empire that became Rome’s great rival in the East.

Background: a fragile Seleucid east

After the death of Alexander the Great in 323 BC, his Asian conquests passed to one of his generals, Seleucus I. The Seleucid Empire he built stretched from the Aegean coast to the borders of India, but its eastern provinces were far from the royal centres in Syria and Mesopotamia.

Parthia was one of these provinces. It lay roughly in what is now north-eastern Iran and southern Turkmenistan, a land of fertile valleys beneath the Kopet Dag mountains, open to the steppe on its northern side. It was governed by a satrap, or provincial governor, appointed by the Seleucid king.

In the middle of the 3rd century BC the Seleucids were weakened by wars with Ptolemaic Egypt and by quarrels within the royal family. Around 245 BC Andragoras, the satrap of Parthia, appears to have broken away and ruled on his own account, issuing coins in his own name. At about the same time Diodotus, the governor of Bactria further east, also asserted independence. The eastern frontier was loosening.

Who were the Parni?

The Parni (also called Aparni) were one of the tribes of the Dahae, an Iranian-speaking nomadic confederation that grazed its herds on the steppes east of the Caspian, near the lower Ochus river (often linked with the Tejen or an old course of the Amu Darya). The Greek geographer Strabo describes Arsaces as a Scythian, the term Greeks used loosely for steppe peoples, who led a group of the Parni.

The Parni were horsemen and archers, used to raiding settled lands. Over time they adopted the language and culture of the Parthians they conquered. This is why the state they founded is known as Parthian rather than Parnian, and why its later rulers wrote in the Parthian language.

How Arsaces took Parthia

The sources for these events are late and brief. The main account comes from Justin, a Roman writer who summarised a lost history by Pompeius Trogus, written around the time of Augustus. Fragments of a lost history by Arrian, preserved by later Byzantine writers, add a few details.

According to Justin, Arsaces was a man “of uncertain origin but proven courage” who lived by raiding. Taking advantage of Seleucid troubles, he invaded Parthia with a band of followers, defeated and killed Andragoras, and took over the province. This is usually dated to around 238 BC. Soon afterwards he also seized Hyrcania, the fertile land along the south-eastern shore of the Caspian.

Arrian’s fragments tell a different story. They name two brothers, Arsaces and Tiridates, who killed a Seleucid governor called Pherecles after he insulted one of them. Historians have long debated how to reconcile the versions. Many now think the governor was Andragoras and that Tiridates may never have existed as a separate ruler.

The Parthian calendar, known as the Arsacid era, began in spring 247 BC. This date probably marks the moment Arsaces was proclaimed king. According to the later writer Isidore of Charax, the ceremony took place at a town called Asaak, where an eternal fire was kept in his honour.

Surviving the Seleucid counter-attack

The new kingdom was soon tested. Seleucus II, the Seleucid king, led an expedition to the east, probably in the late 230s or 220s BC. Justin says Arsaces withdrew to the steppe among a people called the Apasiacae, then returned and defeated the Seleucid army. The Parthians later celebrated this victory as the true start of their independence.

Seleucus was then forced to turn back west to deal with a revolt by his brother, Antiochus Hierax. Arsaces used the respite to strengthen his position. He built fortifications and founded a city named Dara on a mountain called Apaortenon, a site that has not been firmly identified. He also secured peace with Diodotus II of Bactria, removing a threat from the east.

Arsaces probably died around 217 BC, though some scholars place his death a few years later. He was succeeded by his son, known to historians as Arsaces II.

Key people

• Arsaces I (died c. 217 BC): leader of the Parni and founder of the Arsacid dynasty. Coins attributed to him show a beardless man wearing a soft felt cap with ear flaps, and on the reverse an archer seated holding a bow.
• Andragoras: Seleucid satrap of Parthia who broke away from the empire around 245 BC and was overthrown and killed by Arsaces.
• Seleucus II Callinicus (reigned 246–225 BC): Seleucid king whose eastern campaign failed to destroy the new state.
• Diodotus I and II: rulers of Bactria who founded the Greco-Bactrian kingdom at about the same time.
• Arsaces II: son and successor of Arsaces I, who faced the eastern campaign of Antiochus III.

From frontier kingdom to empire

The early Parthian state remained small and vulnerable. Around 209 BC the energetic Seleucid king Antiochus III marched east, captured the Parthian city of Hecatompylos and besieged Sirynx in Hyrcania. Arsaces II was forced to make peace and probably recognised Seleucid overlordship.

The great expansion came under Mithridates I (reigned c. 171–132 BC). He conquered Media and in 141 BC took Seleucia on the Tigris, the greatest city of Mesopotamia. His successors held the Iranian plateau and Mesopotamia, and the Parthian court eventually settled at Ctesiphon, across the Tigris from Seleucia.

An important early centre was Nisa, near modern Ashgabat in Turkmenistan. Excavations at Old Nisa, known in antiquity as Mithradatkert, have revealed palaces, temples, and ivory drinking horns in a mixed Greek and Iranian style. See Nisa, the early Parthian royal city.

Myths and facts

Myth: Parthia was founded in a single year, 247 BC. The Arsacid era began in 247 BC, but the conquest of the province of Parthia came roughly a decade later. The founding was a process spread over many years.

Myth: the Parthians were a primitive nomadic people. The Parni had nomadic roots, but the Arsacid state ruled great cities, used Greek and Parthian for administration, and struck a long, careful series of silver coins.

Fact: the founder’s name became a title. Almost every later Parthian king styled himself Arsaces on his coins. Roman and Greek writers sometimes used “Arsaces” simply to mean “the king of Parthia”.

Timeline

• 247 BC, spring: Start of the Arsacid era, probably marking the proclamation of Arsaces as king.
• c. 245 BC: Andragoras, Seleucid satrap of Parthia, appears to break away from the empire.
• c. 238 BC: The Parni under Arsaces invade Parthia and kill Andragoras.
• Shortly after c. 238 BC: Arsaces takes Hyrcania on the Caspian shore.
• Late 230s or 220s BC: Seleucus II campaigns against Parthia but is forced to withdraw.
• c. 217 BC: Death of Arsaces I; his son Arsaces II succeeds.
• c. 209 BC: Antiochus III invades and Arsaces II makes peace.
• 141 BC: Mithridates I captures Seleucia on the Tigris.
• AD 224: The last Arsacid king, Artabanus IV, is defeated at the Battle of Hormozdgan.

Legacy

The Arsacid dynasty lasted about 470 years, longer than any other ruling house of ancient Iran. At its height it controlled lands from the Euphrates to the borders of modern Afghanistan and sat astride the trade routes that linked the Mediterranean to Central Asia and China.

For Rome, Parthia became the one power in the East it could never subdue. The clash began in earnest at the Battle of Carrhae in 53 BC and continued, on and off, for nearly three centuries.

Within Iran, the Arsacids preserved and passed on traditions of kingship, horse warfare and Iranian religion that their Sasanian successors would inherit. Yet because they left few written records of their own, much of their history is known only from Greek, Roman, Babylonian and Chinese sources.

Why it matters

Arsaces I turned a band of steppe raiders into the founders of a major empire. The state he created ended Greek rule on the Iranian plateau, became Rome’s equal in the East, and shaped the politics of Western Asia for almost five centuries.