In the Parthian system there was one anomaly of a very curious character.  The Greek towns, which were scattered in large numbers throughout the Empire, enjoyed a municipal government of their own, and in some cases were almost independent communities, the Parthian kings exercising over them little or no control.  The great city of Seleucia on the Tigris was the most important of all these:  its population was estimated in the first century after Christ at six hundred thousand souls; it had strong walls, and was surrounded by a most fertile territory.  It had its own senate, or municipal council, of three hundred members, elected by the people to rule them from among the wealthiest and best educated of the citizens.  Under ordinary circumstances it enjoyed the blessing of complete self-government, and was entirely free from Parthian interference, paying no doubt its tribute, but otherwise holding the position of a “free city.”  It was only in the case of internal dissensions that these advantages were lost, and the Parthian soldiery, invited within the walls, arranged the quarrels of parties, and settled the constitution of the State at its pleasure.  Privileges of a similar character, though, probably, less extensive, belonged (it would seem) to most of the other Greek cities of the Empire.  The Parthian monarchs thought it polite to favor them; and their practice justified the title of “Phil-Hellene,” which they were fond of assuming upon their coins.  On the whole, the policy may have been wise, but it diminished the unity of the Empire; and there were times when serious danger arose from it.  The Syro-Macedonian monarchs could always count with certainty on having powerful friends in Parthia, whatever portion of it they invaded; and even the Romans, though their ethnic connection with the cities was not so close, were sometimes indebted to them for very important assistance.

We are told that Mithridates I., after effecting his conquests, made a collection of the best laws which he found to prevail among the various subject peoples, and imposed them upon the Parthian nation.  This statement is, no doubt, an exaggeration; but we may attribute, with some reason, to Mithridates the introduction at this time of various practices and usages, whereby the Parthian Court was assimilated to those of the earlier Great Monarchies of Asia, and became in the eyes of foreigners the successor and representative of the old Assyrian and Persian Kingdoms.  The assumption of new titles and of a new state—­the organization of the Court on a new plan—­the bestowal of a new character on the subordinate officers of the Empire, were suitable to the new phase of its life on which the monarchy had now entered, and may with the highest probability, if not with absolute certainty, be assigned to this period.