Parthia was an Iranian civilization situated in the northeast of modern Iran, but at its height covering all of Iran proper, as well as regions of the modern countries of Armenia, Iraq, Georgia, eastern Turkey, eastern Syria, Turkmenistan, Afghanistan, Tajikistan, Pakistan, Kuwait, the Persian Gulf coast of Saudi Arabia, Bahrain, Qatar, and UAE.
Parthia was led by the Arsacid dynasty (Middle Persian: اشکانیان Ashkâniân), which reunited and ruled over the Iranian plateau, after defeating the Seleucids, beginning in the late 3rd century BC, and intermittently controlled Mesopotamia between ca 150 BC and AD 224. It was the third native dynasty of ancient Iran (after the Median and the Achaemenid dynasties). Parthia (mostly due to their invention of heavy cavalry) was the arch-enemy of the Roman Empire in the east; and it limited Rome's expansion beyond Cappadocia (eastern Anatolia).
After the Scythian-Parni nomads (Assyrians called them Ashkuz) had settled in Parthia and had built a small independent kingdom, they rose to power under king Mithridates the Great (171–138 BC). Later, at the height of their power, Parthian influence reached as far as Ubar in Arabia, the nexus of the frankincense trade route, where Parthian-inspired ceramics have been found. The power of the early Parthian empire seems to have been overestimated by some ancient historians, who could not clearly separate the powerful later empire from its more humble obscure origins. The end of this long-lived empire came in AD 224, when the empire was loosely organized and the last king was defeated by one of the empire's vassals, the Persians of the Sassanid dynasty.
Little is known of the Parthians; not much of their own literature has survived. Consequently Parthian history is largely derived from foreign histories, controlled by the evidence of coins and inscriptions; even their own name for themselves is debatable due to a lack of domestic records. Several Greek authors, of whom we have fragments, including Apollodorus of Artemita and Isidore of Charax, wrote under Parthian rule. Their power was based on a combination of the guerilla warfare of a mounted nomadic tribe, with organisational skills sufficient to build and administer a vast empire - even though it never matched in power the Persian empires that preceded and followed it. Vassal kingdoms seem to have made up a large part of their territory (see Tigranes II of Armenia), and Hellenistic cities enjoyed a certain autonomy; their craftsmen received employment by some Parthians.
Strabo considered Parthians to be Carduchi, inhabitants of Kurdistan.