Isdigerd remained tranquil and at rest within the walls of his capital.

Assuming as his special title the characteristic epithet of "Ramashtras," "the most quiet," or "the most firm," he justified his assumption of it by a complete abstinence from all military expeditions.
When Isdigerd had reigned peaceably for the space of nine years, he is said to have received a compliment of an unusual character.

Arcadius, the emperor of the East, finding his end approaching, and anxious to secure a protector for his son Theodosius, a boy of tender age, instead of committing him to the charge of his uncle Honorius, or selecting a guardian for him from among his own subjects, by a formal testamentary act, we are told, placed his child under the protection of the Persian monarch.

He accompanied the appointment by a solemn appeal to the magnanimity of Isdigerd, whom he exhorted at some length to defend with all his force, and guide with his best wisdom, the young king and his kingdom.

According to one writer, he further appended to this trust a valuable legacy--no less than a thousand pounds weight of pure gold, which he begged his Persian brother to accept as a token of his goodwill.