his, however, is not
the case absolutely. The spur itself is penetrable by two passes, one
where it joins the Elburz, which is the more difficult of the two, and
another, further to the south, which is easier. The latter now known
as the Girduni Sudurrah pass, constitutes the famous "Pylae Caspiae."
Through this pass alone can armies proceed from Armenia, Media, and
Persia eastward, or from Turkestan, Khorasan, and Afghanistan into the
more western parts of Asia. The position is therefore one of primary
importance. It was to guard it that Rhages was built so near the eastern
end of its territory. So long as it remained in the possession of Syria,
Parthian aggression was checked. Rhagiana, the rest of Media, and the
other provinces were safe, or nearly so. On the other hand, the loss of
it to Parthia laid the eastern provinces open to her, and was at once
almost equivalent to the loss of all Rhagiana, which had no other
natural protection. Now we find that Phraates surmounted the "Gates,"
and effected a lodgment in the plain country beyond them. He removed a
portion of the conquered Mardians from their mountain homes to the city
of Charax, which was on the western side of the Gates, probably on the
site now occupied by the ruins known as Uewanikif. Their location in
this strong post was a menace to the neighboring town of Rhages, which
can scarcely have maintained itself long against an enemy encamped at
its doors. We are not informed, however, of any results which followed
on the occupation of Charax during the lifetime of Phraates. His reign
lasted only seven years--from B.C. 181 to B.C. 174--and it is thus
probable that he died before there was time for his second important
conquest to have any further consequences.

Phraates had sufficient warning of his coming decease to make
preparations with respect to a successor. Though he had several sons,
some of whom were (we must suppose) of sufficient age to have ascended
the throne, he left his crown to his brother, Mithridates. He felt,
probably, that the State required the direction of a firm hand, that war
might at any time break out with either Syria or Bactria; while, if
the career of conquest on which he had made Parthia enter were to be
pursued, he could trust his brother better than any of his sons to
conduct aggressive expeditions with combined vigor and prudence. We
shall see, as the history proceeds, how Mithridates justified his
choice. Phraates would also appe