The Parni were one of the three Dahae tribes of Scythian origin who battled against Alexander the Great during his conquest of their homeland along the Oxus River. Insurgent under Arsaces, they fought against the Greek Successor Kingdoms from 247-130 BC and during this time they expanded their frontiers until they found themselves in possession of territories stretching between Armenia and India, utilising both Pahlavi-Parthian and Greek dialects. This was the Parthian Empire, ruled by an absolute monarch of the Arsacid Dynasty and Zoroastrian faith. Most records of Parthian civilisation come from irate Greeks or Romans and most historical sources focus on Parthian military tactics - an accurate measure both of their character and that of their foes.
The Parthian army was largely composed of horse archers, created from an expansive body of slaves and retainers. These horse archers were lightly armoured (mostly in cloth and leather) for the sake of mobility and were equipped with thumb rings (developed in the steppe lands around 200 BC), which primarily allowed for an easier loose. Parthian skirmishing tactics involved the horse archers lining up in a loose wedge formation, charging forward and firing at around 90 metres, wheeling at 45 metres and loosing another shot as they retreated. Although most Asiatic nomads practised this combat technique, it became widely known as the Parthian shot and may have been adopted by western Chinese nomads. By surrounding a less mobile (for instance, Roman) enemy and creating a bewildering swarm, the enemy became demoralised and could be cut down by heavier cavalry as they retreated.
The Parthian (under Orodes II) defeat of forty thousand Roman soldiers (under Crassus, who was treacherously killed during negotiations) at the Battle of Carrhae in 53 BC illustrated an important fact of the comparative characteristics of the Parthian and Roman armies; whereas the Parthians mostly employed swift horse archers and heavy cataphract-style cavalry (the design of the latter being adopted by the later Roman, or Byzantine Empire), the Romans primarily relied on infantry and the comparatively lightly armoured equestrian soldiers. Parthia, therefore, had the advantage of mobility and range. The Romans would make few advances into Mesopotamia as a result of this difficulty; for all its strengths the Roman army was rigid, although the testudo (locked-shield) formation was developed in order to counter such methods of attack. The Parthians, as they expanded and settled, began to hire mercenary infantry to supplement their cavalry.
Parthia’s greatest power, though, even during times of Roman incursion, was in its control of commerce: the famous Chinese Silk Road became better-established when the Parthian and Roman Empires arose. Contact, even with western China, had until that time been minimal. The Parthians are credited for acting as intermediaries for the traders who crossed the world with their goods, not least because the bartering system which prevailed in western Asia was replaced by a more efficient monetary system. The volume of trade which passed through Greek-founded cities of the eastern Mediterranean is believed to have been far greater than levels of commerce during either the Athenian or Carthaginian Empires. Palmyra, Ctesiphon, Seleucis and Damascus were some of the wealthiest cities in the Mediterranean world during this time. Rome made several attempts to seize or circumvent Parthian trade centres, but these were ephemeral acquisitions at best - Roman patricians continued to pay heavy Parthian taxes for the miniscule quantities of luxury goods which defined their status.
Parthian coins are usually ambiguous as to the ruler they depict, although the name ‘Arsaces’ appears in Greek on almost all of them and Parthian rulers can be identified by their apparel, which is highly reminiscent of Scythian designs. Most coins were produced by the royal mints, although the dependencies of Characene, Elymais and Persis were permitted to mint their own, and some conquered cities were allowed to distribute local currencies. The broad distribution of coins (as far as the Volga River, Caucasus Mountains and Chinese Turkestan; Parthian trade routes could even access goods from Siberia) provides evidence of Parthian trading power. Coins were minted in both silver and gold. Other evidence of Parthian life can be found in their art and architecture. Buildings were generally constructed of baked mud-brick, with vaulted ceilings. Reliefs, often figurative or geometric in nature, abounded and statues depicting monarchs (occasionally linked to cult activity) were common, especially in mortuary buildings and in palaces. Parthian jewellery was highly elaborate and was often accompanied by the use of cosmetics, suggesting a strong cultural emphasis on physical beauty. Recurring representations of celestial bodies in both art and architecture stress the importance of astrology.
Conflict between the Romans and Parthians must be understood in the light of Roman ignorance of eastern customs and vice versa. The Roman system of government was designed to administer a city-state: hence, little expansion took place during the early period and most wars were preventive in nature. Roman interference in eastern affairs during its more conservative period ensured that the two civilisations were bound to come into conflict, as Rome had developed a pathological fear of a new threat emerging from the hated east (particularly Persia, as it had long been wealthy and militarily powerful before Greek conquest). Rome and Parthia had a lengthy history of conflict, including the Battle of Carrhae and persistent raiding of Syria (which caused no end of trouble for Mark Antony, who lost twenty thousand men and a supply train to Armenian treachery when he moved to counter Parthian aggression, leading him to greater reliance on Cleopatra).
Armenia, long an independent entity which antagonised both Rome and Parthia, would (after the defeat of Antony and the rise of Augustus) become a buffer state, with diplomatic struggles constantly pitching the balance of power. The Roman upper echelons were further affronted by the placement of the Parthian King Vologases’ brother Tiridates on the throne of Armenia, insisting that the latter acknowledge Roman authority in the region and demanding that he come to Rome to be crowned. This occurred under the reign of Nero; Augustus had correctly judged that the Parthians were not as great a threat as most imagined (leaving only five legions to secure Syria), as it was torn by its own internal diplomatic and dynastic struggles, with many Parthian territories spontaneously declaring independence or minor princes inducing civil wars. His insights into the east were not shared by most of his successors.
Conflict again arose when Chosroes, the Parthian ruler during Trajan’s reign, placed a relative on the throne without asking for Rome’s endorsement - a direct contravention of the settlement reached under Nero by the general Corbulo. Trajan chose a moment of internal conflict in Parthia to push his frontiers to Ctesiphon, securing the new province of Assyria and corresponding trade routes to India. Trajan’s conquests (which took eastern trade from Parthian hands) quickly evaporated as little effort had been spent on consolidation (and Jewish revolts erupted in the cities of the Levant); Armenia and Assyria were lost, but northern Mesopotamia became a vassal kingdom which endured even after Trajan’s death in 116 AD. The Parthians gave every indication of abiding by the treaty of cession, but Roman paranoia survived and were it not for the outbreak of plague in the east, Marcus Aurelius would likely have led a successful conquest to the heart of Parthia. As it was, the Roman defensive position was nonetheless strengthened (as Armenia was made a client kingdom) and that of the Parthians proportionally weakened. The downfall of the Parthian Empire would be due to a conjunction of Roman hostilities (under Septimius and Caracalla) and the rise of the Sassanids in the province of Pars in 228 AD. The Sassanids, in turn, would survive until Islamic conquest in the seventh century AD.
Sources
Books:
Warfare in the Classical World, John Warry
The World of Ancient Times, Carl Roebuck
Internet
http://www.parthia.com/
http://www.iranica.com/
http://campus.northpark.edu/history/WebChron/MiddleEast/Parthian.html
http://www.iranchamber.com/history/parthians/parthians.php