At any rate, in the interval between A.D.
351 and 359, probably while Sapor was engaged in the far East, Arsaces sent envoys to Constantinople with a request to Constantius that he would give him in marriage a member of the Imperial house.

Constantius was charmed with the application made to him, and at once accepted the proposal.

He selected for the proffered honor a certain Olympias, the daughter of Ablabius, a Praetorian prefect, and lately the betrothed bride of his own brother, Constans; and sent her to Armenia, where Arsaces welcomed her, and made her (as it would seem) his chief wife, provoking thereby the jealousy and aversion of his previous sultana, a native Armenian, named Pharandzem.

The engagement thus entered into led on, naturally, to the conclusion of a formal alliance between Rome and Armenia--an alliance which Sapor made fruitless efforts to disturb, and which continued unimpaired down to the time A.D.359 when hostilities once more broke out between Rome and Persia.
Of Sapor's Eastern wars we have no detailed account.

They seem to have occupied him from A.D.350 to A.D.357, and to have been, on the whole, successful.