 Prior to the Arab invasions, Rshtuni had been appointed the "sparapet" (commander-in-chief) of the Armenian forces in the Armenian Marzpanate and was appointed as the "marzban" of Armenia in 634.He defended, alongside the Byzantine General Procopius, against the first, unsuccessful, Arab attack into Armenia in 640.He was unable to prevent the Arabs from pillaging the capital of Dvin in 642.