The Parthians do not appear in history until a comparatively recent period.  Their name occurs nowhere in the Old Testament Scriptures.  They obtain no mention in the Zendavesta.  The Assyrian Inscriptions are wholly silent concerning them.  It is not until the time of Darius Hystaspis that we have trustworthy evidence of their existence as a distinct people.  In the inscriptions of this king we find their country included under the name of Parthva or Parthwa among the provinces of the Persian Empire, joined in two places with Sarangia, Aria, Chorasmia, Bactria, and Sogdiana, and in a third with these same countries and Sagartia.  We find, moreover, an account of a rebellion in which the Parthians took part.  In the troubles which broke out upon the death of the Pseudo-Smerdis, B.C. 521, Parthia revolted, in conjunction (as it would seem) with Hyrcania, espousing the cause of that Median pretender, who, declaring himself a descendant of the old Median monarchs, set himself up as a rival to Darius.  Hytaspes, the father of Darius, held at this time the Parthian satrapy.  In two battles within the limits of his province he defeated the rebels, who must have brought into the field a considerable force, since in one of the two engagements they lost in killed and prisoners between 10,000 and 11,000 men.  After their second defeat the Parthians made their submission, and once more acknowledged Darius for their sovereign.

With these earliest Oriental notices of the Parthians agree entirely such passages as contain any mention of them in the more ancient literature of the Greeks.  Hecatseus of Miletus, who was contemporary with Darius Hystaspis, made the Parthians adjoin upon the Chorasmians in the account which he gave of the geography of Asia.  Herodotus spoke of them as a people subject to the Persians in the reign of Darius, and assigned them to the sixteenth satrapy, which comprised also the Arians, the Sogdians, and the Chorasmians.  He said that they took part in the expedition of Xerxes against Greece (B.C. 480), serving in the army on foot under the same commander as the Chorasmians, and equipped like them with bows and arrows, and with spears of no great length.  In another passage he mentioned their being compelled to pay the Persian water tax, and spoke of the great need which they had of water for the irrigation of their millet and sesame crops.

It is evident that these notices agree with the Persian accounts, both as to the locality of the Parthians and as to the fact of their subjection to the Persian government.  They further agree in assigning to the Parthians a respectable military character, yet one of no very special eminency.  On the ethnology of the nation, and the circumstances under which the country became an integral part of the Persian dominions, they throw no light.  We have still to seek an answer to the questions, “Who were the Parthians?” and “How did they become Persian subjects?”