Capital of modern Kurdistan, in eastern Iraq. It was already inhabited in the 4th millennium BC; in the oldest cuneiform texts it is called Urbilum (Assyrian Arbaʾilu). One of the stations along the royal road between Sardes and Persepolis, it was a cultic center, with a temple devoted to the fertility goddess Ishtar, as well as a center of commerce and a main point on the caravan routes. It was held successively by the Babylonians, Persians, and Greeks, and it was very near Arbela that Darius III was defeated by Alexander the Great (331 BC). It was during Alexander’s rule that the country surrounding Arbela became known as Adiabene (Syr. Ḥadyāb), which later became part of the Parthian Empire, and eventually a governor’s seat during the Sasanian period. In the 1st cent. AD, Adiabene became an independent kingdom, subject to the Parthian king, but it remained on the periphery of the battle zone between Rome and Parthia. It was in Adiabene, according to Josephus, that the royal family converted to Judaism in the 1st cent. AD.

Arbela was christianized at a very early date and its inhabitants quickly became the victims of persecution by the local governor. The history of its Christian beginnings is recounted in the Chronicle of Arbela, a late and dubious mélange of biographical sketches of the twenty early bishops of Arbela (ca. 104–511). According to this Chronicle, Pekhida, a disciple of Addai, became the first bp.; during the tenure of Isḥaq, the third bp., the first church in Arbela was built. The Chronicle also bears testimony — and this may be the most historical witness of this text — that many of Arbela’s bishops and faithful suffered martyrdom at the hands of the Persians. The Acts of Mari, a seemingly more reliable source, claims rather that Aggai and Mari, missionaries from Edessa, were the first evangelists of Adiabene, and its first bps. Arbela was for some time the metropolitan seat of the region of Adiabene, and boasted of several important figures as bishops — of whom three later became patriarchs  — who appear in the signatory lists of the synods of the Ch. of E. A Christian school located in Arbela also produced a number of important monastic figures and bps. In 1295, a second Mongol invasion destroyed the Christian churches, killed many Christians, and drove the surviving Christians into other regions. Subsequent persecutions were sufficiently harsh that, by the end of the 17th cent., there were no remaining Christians in Arbela; small groups had begun to re-immigrate in the early part of the 20th cent.