In 247 BC, Aršak, or Arsaces as he was later known, leader of the Parni, a branch of the Dahae Scyths, was crowned king. This name may very well be his clan title rather than his given name. As we see in later Parthian times, the tradition of having a 'family' or tribal name was quite common among the Parthian nobles. Families of Suren, Karen, Espahbad, Naudar, and other Parthian noble families all carried their personal names as well as the above family names. Additionally, the tradition of having a regal name was also common from the Achaemenid times, as almost all Achaemenid emperors after Darius II seem to have chosen a dynastic name upon their accession.

It was he who led his people south and overthrew the Seleukid governor of Parthia in 238 BC, this same governor, who was himself in revolt against his overlords. He would establish a kingdom that would last for almost 500 years. At the height of their power, the Parthians were second only to Rome and were the only civilized nation able to stand up to her.

Parthia's beginnings were not easy. Arsaces I, initially controlled little more than Parthia, and neighbouring Hyrcania and they faced vigorous Seleukid attempts to recapture those lost dominions. In 226 BCE and again in 210 BCE, the Seleukids invaded in force. The Parthians retreated before them, only to return seizing yet more land when Seleukid attention fatally drifted towards the Hellenic western part of their empire. By the mid century things had changed. After a long war, the Parthian king Mithradates I had conquered Media and invaded Mesopotamia. This time, the Seleukid counterattack was fought and totally defeated. The Seleukid king Demetrios II, was captured and held prisoner, and upon his death Mithradates I ruled over Parthia, Hyrcania, Media, Babylonia, Assyria, Elymais and Persis. Parthia was now to be a world power.

When the Parthian kingdom was founded in the mid 3rd century BC, it was made up of a small Scythian tribe, the Parni, and it’s army was relatively small consisting chiefly of horse archers and the better armoured tribal chieftains. These skilled riders were served as part of the tribal host only in times of war. When the war was over, these warriors returned home with their loot to their everyday lives. As a result, their concepts of war was confined to raids and counter raids. Through out this period the Parthians remained a semi- nomadic people who made their living from horse and cattle breeding. However, contact with Persian style of warfare and the changing needs of a society no longer based on a nomadic lifestyle brought new concepts of warfare. This settled existence not only eroded their steppe culture but probably caused a rapid erosion of their horse and archery skills as well.

Theoretically the Parthian king could call upon all those within the realm to serve in his armies. The Arascid king's major stumbling block was his own Azad nobles. The royal council was comprised the representatives of the Parthian clans, towns and vassal states. The only obligation some of these vassal states had to the Arascid dynasty was supplying troops for military service. However this council was effectively controlled by the lords of the Seven Great Clans. As a result the kings relied heavily on their own hereditary lands for the core of their armies. This was supplemented by Sakae nomadic mercenaries and those Nobles of the realm with a vested interest of advancing their fortunes by such service.

Parthian armies had to operate in all types of terrain and climates from the hot flatlands of Aryavarta which would later be called India, the arid central plateau of Iran, the cold northern steppes and the high mountains of Armenia and Gandhara. Their enemies varied from slow-moving pikemen of the Hellenic armies to their nimble and swift kin from the eastern steppe. Parthian military thinking was therefore based on the ideas of mobility, adaptability and self-sufficiency, it could be no other way. The plan of any battle was the Cataphract charge, a massed attack knee-to-knee by heavy cavalry, the light horse archers supported this by probing for weak points to be exploited with concentrated archery. The archers did terrible damage to massed troops and this would force the enemy to disperse. If they did so, they left themselves exposed to the charge of the heavy Cataphracts. With the light and heavy cavalry deployed, the Pahlavan cavalry was able to bring down of one form of attack, or the other as the situation dictated. It was this tactic that shattered the Roman legions at the battle of Carrhae.

The tribal host formed the bulk of the Parthian army and would have provided the bulk of the Hamspah or levies, mounted archers and the infantry levy. Each clan Family mustered under their Wuzurgan grandees and the lesser Azadan leaders, bringing with them retainers from their lands and these would fight together in the same units. They used probably the best weapon for the horseman, which was the composite horse bow. This was similar to the simple bow but used multiple types of wood, horn and sinew to produce a stronger bow with a greater draw weight, the force built up in the string that will propel the arrow forward to its target.

The wars between the Greeks and the Persians and final Alexandrian conquest showed the Pahlava that lightly armed infantry could not stop heavy, well-trained, infantry of the type employed by the Greeks and later Romans. They themselves had a healthy contempt for such light infantry in their many raids of more civilized lands. These heavy infantry could only be countered with heavily armed cataphracts and tough veteran horse archers able to cause disorder in the massed ranks and then attacking vulnerable points with archery and lance. This was a lesson they learned well and would prove on the field of battle. The Romans and Greeks came to respect the Parthian in a way they never respected the Persian.

The Parthian Kingdom was smaller than that of the Achaemenid Persians, and closer in many ways to later european feudal states. There was for example no standing army, just as in feudal europe. There were of course the garrisons of the Hellenic Polis and vital forts were garrisoned. The armed retinues of the Wuzurgan grandees, the Azadan minor nobility, Zandbed and Dehbed tribal chiefs, along with the local kings, Šahrdaran, and princes of royal blood, the Waspuhragan.

The Great King as Sar-Xwaday, Overlord, appealed to his subordinate kings, the Šahrdaran, the Azad nobles, garrison commanders, and most importantly the tribal lords to muster what they could and bring them to an appointed place at a given time. The assembled host would be placed under the command of a Spahbed or general, trusted by the Great King. The core of the army, or Spad was the feudal or tribal nobility. Accustomed to hard riding from an early age and skilled in archery and skirmishing, the Pahlavan cavalry would come to be known as something to fear. Their name echoes in eternity as the term Pahlavan, means Hero in Persian.

The Pahlavan nation was ever under threat, and they never suffered for a lack of enemies. The North Iranian nomads, the Dahae, Sakae, and Sauromatae constantly threatened the eastern borders while in the west first the Seleukids and then the Romans were ever ready for full scale war. Few nations have ever faced such a combination of enemies and finding an army that would both was no easy matter. Rapid mobility was essential for no slow moving army could possibly match the light cavalry of the nomads to the north. Infantry were not very useful in such a situation and not worth what Romans or Greeks paid for them. The answer was the Asabaran, pronounced Asavaran in Parthian. The Parthians did have foot soldiers and when large numbers of Greeks or Romans were captured they had no hesitation in putting them to use. They could however never be more than a small part of the Parthian army. They could not afford to maintain a massive army of heavy infantry to counter the nomadic cavalry, nor could the Romans, who when faced with this same situation, took to the same solution.

The mainstay of the infantry were foot archers. These foot archers almost certainly represented the poorer elements of the various infantry levies of Parthia. The tradition of mounted archery in Parthia and the northern steppe peoples makes it almost inevitable that a massed levy would produce significant numbers of foot archers as well.

When Persia was conquered by Alexander the Great, Alexander originally attempt to bring a fusion of Persian and Greek culture. However this attempt at a fusion was to collapse upon his death, and lead to the alienation of the Persian elite and the rejection of Greek culture by the Persians. In Persia kingship and religion were tied together in a way that the Greeks poorly understood. The world had been created by Ahura Mazda and it was he who ordained the monarch. There were those who responded to the appeal of Hellenism but as elsewhere it was associated with a secular spirit repulsive to most near eastern peoples. However, it is also true that Alexander destroyed Zoroastrian sanctuaries, persecuted priests and destroyed religious writings. In doing so the 'accursed Alexander' created an army of priests who saw Hellenism as the enemies. In addition to their religious duties, these priests served as judges, tax collectors and scribes. They were in a unique position to do harm to the Greek cause in Iran.

Traditional Zoroastrianism was revived slowly under the Parthian, or Arsacid, dynasty, which ruled from about 250 bc to ad 224. By the time of the Sassanid dynasty, from ad 224 to 651, Zoroastrianism had become the popular religion among most groups in Iran and Central Asia and was practiced from the Middle East to the western border of China.

Their empire began to decline in the 2nd century AD, as Parthia was chronically weakened by internal struggle, and the rebellion of Ardashir of Persis in 220 AD sounded its death knell. Such bloody conflicts were not uncommon within the ruling Arsacid family and the loyalty of the great noble lords was often dubious. The last Parthian king, Artabanos IV, was killed in the battle of Hormuzdagan in 224 AD and Ardashir was crowned as the first Sassanid king. The first acts of the Sassanid dynasty was the systematic destruction of everything Parthian and under the hammer and fire of Sassanid fury went the records of what had once been a proud nation.