All our historical sources support the view taken above that Edessa, the capital of the kingdom which the Greeks and Romans called Osrhoene, was the earliest seat of Christianity in Mesopotamia and the cradle of Syriac literature.
In all probability the first king of Osrhoene to adopt Christianity was Abgar IX., son of Ma'nu, who reigned from A.D.
ABGAR, a name or title borne by a line of kings or toparchs, apparently twenty-nine in number, who reigned in Osrhoene and had their capital at Edessa about the time of the Christian era.
Although the beginnings of Christianity at Edessa are enshrouded in the mists of legend, and the first mention of Christian communities in Osrhoene and the towns there is connected with the part they played in the paschal controversy (c. A.D.
In 1031 the emperor recovered Edessa; but in 1040 it fell into the hands of the Seljuks, whose progress had added a large element of Armenian refugees to the population of Osrhoene.