Parthian Empire Founded

In the middle of the third century BCE, Arsaces I, the leader of a nomadic people known as the Parni, established a new kingdom in the northeast of the Iranian world. Over the following generations his Arsacid dynasty grew into the Parthian Empire, which dominated Iran and Mesopotamia until the early third century CE. It was the great rival of Rome in the east, and its control of overland routes linking the Mediterranean to Central Asia and China made it a central power in ancient trade and diplomacy.

The background was the breakup of Alexander the Great's conquests. After his death in 323 BCE, most of the former Persian Empire fell to the Seleucid dynasty, whose kings ruled from Syria and Mesopotamia and relied on Greek settlers and garrisons to hold distant provinces. By the 240s BCE the Seleucids were weakened by wars with Ptolemaic Egypt, and the eastern satrapies were drifting out of their control. Bactria broke away under a Greek-ruled state, and the province of Parthia, southeast of the Caspian Sea, became unstable.

The traditional date of 247 BCE comes from the Parthians' own Arsacid calendar, which counted years from that point. Ancient writers, mostly Greek and Roman and often writing long afterward, give conflicting accounts of how Arsaces came to power. They agree that he led the Parni into Parthia, probably from the steppe region east of the Caspian, and overthrew or displaced the local Seleucid governor. Modern historians debate the details, including his origins and whether the Arsacid era marks a founding, a rebellion or a later commemoration. Early Parthian rule was modest, and the Seleucids made efforts to recover the region.

The kingdom's real expansion came later. Under Mithridates I in the mid-second century BCE, the Parthians took Media and Mesopotamia and captured Seleucia on the Tigris, and their rule reached the Persian Gulf. Their capital moved to Ctesiphon on the Tigris. The empire was decentralized, with regional kings and powerful noble families, and was known for its mounted archers and heavily armored cavalry. Its culture blended Iranian traditions with Hellenistic influences, visible in coinage that used Greek inscriptions.

Parthia's most famous military success was the defeat of the Roman general Crassus at Carrhae in 53 BCE. Afterward, the two powers fought repeatedly over Armenia and Mesopotamia, and also traded. Parthian territory sat along the Silk Road, and the state profited from taxes and from its role as intermediary between Rome and China. The dynasty finally fell in the 220s CE, when Ardashir I, who founded the Sasanian Empire, overthrew the last Arsacid ruler. Much of what we know of Parthia comes from hostile Roman sources, coins and archaeology, since few Parthian texts survive.