The repulse of Callinicus was a probable indication of the fate of all future efforts on the part of Syria to reduce Parthia; the conditions of peace granted by Antiochus to both countries, after a series of military successes, constituted almost a proof that the yoke of Syria would never be re-imposed on either the Parthian or the Bactrian nation.
With the departure of Antiochus from the East, about B.C.206, we enter upon a period when Parthian history is, for a quarter of a century, almost a blank.

Nothing more is known of Arsaces III.

after Antiochus retired; and nothing at all is known of his successor, Priapatius, beyond his name and the length of his reign, which lasted for fifteen years (from about B.C.196 to 181).

The reigns of these princes coincide with those of Euthydemus and his son, Demetrius, in Bactria; and perhaps the most probable solution of the problem of Parthian inactivity at this time is to be found in the great development of Bactrian power which now took place, and the influence which the two neighboring kingdoms naturally exercised upon each other.

When Parthia was strong and aggressive, Bactria was, for the most part, quiet; and when Bactria shows signs of vigorous and active life, Parthia languishes and retires into the shade.
The Bactrian Kingdom, founded (as we have seen) a little before the Parthian, sought from the first its aggrandizement in the East rather than in the West.