The Arianist Valens has fallen under the influence of legists, such as the praetorian prefect Modestus, who has instituted harsh persecutions in Antioch of the educated pagan elite.

Valens has exiled even moderate Nicaean bishops and granted to Arians favors that have aroused violent reactions from the orthodox, whose power has increased in the East, which his policies have made prey to violent religious passions.

Valens banishes bishops who had been restored by Julian, although near the end of his reign he relents somewhat and allows these exiles to return.

After suppressing the conspiracy of Theodorus at Antioch in the winter of 371-372, Valens becomes involved in a new conflict with Persia.