Bp. of Seleucia-Ctesiphon and cath. When Yahbalaha was elected, the Christians in the Persian Empire enjoyed the freedom accorded to them by Emperor Yazdgard I and formally laid down in the Synod of Isḥaq (410). This situation of tolerance must have continued under Isḥaq’s successor, Cath. Aḥai (410–15), about whom very little is known. Our main source about Yahbalaha’s tenure is the Synodicon Orientale, which includes an account of the synod held in 419 or 420, shortly before Yahbalaha’s and Yazdgard’s death (420). Prior to the synod, Yahbalaha had been sent by Yazdgard as an ambassador to the Roman Empire ‘for the peace and the reconciliation of the two empires, which are the robust shoulders of the world’. The Roman Emperor (Theodosius II) responded to Yahbalaha’s mission by sending Aqaq of Amid to Persia. It is during Aqaq’s presence in the Persian capital that the synod was held, Aqaq playing a role similar to the one Marutha of Maypherqaṭ played at the synod of 410.

One important concern of the synod was to boost conformity among Christians in the two empires by adopting the canons issued at various synods in the Roman Empire. In the account of the synod it is said that the process of adjustment between the Christian communities in the two empires, begun in 410, had not been completed and that division and confusion had arisen. Since the account does not include canons, it cannot be ascertained which new rules were introduced, even though there is reason to assume that on this occasion Greek canonical collections were in fact brought to the Ch. of E. The fact that only twelve signatures are found (as compared to the 38 signatures for the 410 synod) may indicate that the synod was not widely supported. Its limited success may also be due to Yazdgard’s changing attitude toward the Christians and to the resumption of persecution around 419. This was a prelude to renewed warfare between the two empires (421–22) and created an atmosphere of crisis, in which Yahbalaha’s successor Dadishoʿ convened the synod of 424.