The power and dignity of the Parthian nobles was greater than that usually enjoyed by any subjects of an Oriental king.  Rank in Parthia being hereditary and not simply official, the “megistanes” were no mere creatures of the monarch, but a class which stood upon its own indefeasible rights.  As they had the privilege of electing to the throne upon a vacancy, and even that of deposing a duly elected monarch, the king could not but stand in wholesome awe of them, and feel compelled to treat them with considerable respect and deference.  Moreover, they were not without a material force calculated to give powerful support to their constitutional privileges.  Each stood at the head of a body of retainers accustomed to bear arms and to serve in the wars of the Empire.  Together these bodies constituted the strength of the army; and though the royal bodyguard might perhaps have been capable of dealing successfully with each group of retainers separately, yet such an esprit de corps was sure to animate the nobles generally, that they would make common cause in case one of their number were attacked, and would support him against the crown with the zeal inspired by self-interest.  Thus the Parthian nobility were far more powerful and independent than any similar class under the Achaemenian, Sassanian, Modern Persian, or Turkish sovereigns.  They exercised a real control over the monarch, and had a voice in the direction of the Empire.  Like the great feudal vassals of the Middle Ages, they from time to time quarrelled with their liege lord, and disturbed the tranquillity of the kingdom by prolonged and dangerous civil wars; but these contentions served to keep alive a vigor, a life, and a spirit of sturdy independence very unusual in the East, and gave a stubborn strength to the Parthian monarchy, in which Oriental governments have for the most part been wanting.

There were probably several grades of rank among the nobles.  The highest dignity in the kingdom, next to the Crown, was that of Surena, or “Field-Marshal;” and this position was hereditary in a particular family, which can have stood but a little below the royal house in wealth and consequence.  The head of this noble house is stated to have at one time brought into the field as many as 10,000 retainers and slaves, of whom a thousand were heavy-armed.  It was his right to place the diadem on the king’s brow at his coronation.  The other nobles lived for the most part on their domains, but took the field at the head of their retainers in case of war, and in peace sometimes served the offices of satrap, vizier, or royal councillor.  The wealth of the class was great; its members were inclined to be turbulent, and, like the barons of the European kingdoms, acted as a constant check and counterpoise to the royal dignity.