The king so called had reached when elected the advanced age of eighty.

It may be suspected that he was a son of the sixth Arsaces (Mithridates I.), and consequently a brother of Phraates II.

He had, perhaps, been made prisoner by that Scythians in the course of the disastrous war waged by that monarch, and had been retained in captivity for above fifty years.

At any rate, he appears to have been indebted to the Scythians in some measure for the crown which he acquired so tardily, his enjoyment of it having been secured by the help of a contingent of troops furnished to him by the Scythian tribe of the Sacauracae.
The position of the Empire at the time of his accession was one of considerable difficulty.

Parthia, during the period of her civil contentions, had lost much ground in the west, having been deprived by Tigranes of at least two important provinces.