Read Edessa first
Seleucus I, a Macedonian officer under Alexander the Great, established an outpost in this already settled town for his newly formed kingdom in 303 B.C., twenty years after the death of Alexander. He named it Edessa after the city of the same name in Macedonia. By about 132 B.C. the dynasty he established, the Seleucid dynasty, collapsed and the city came under the control of the Abgar dynasty, a series of client kings for Parthia, very much the way Herod I and Herod Antipas were client kings of Israel under Roman control. In the years that followed the Abgar dynasty, which lasted for 350 years, Edessa fell under Armenian, Persian and Roman control. It would become part of Byzantine Empire. It repulsed the Persians in A.D. 544, but fell to Muslim Arabs in 639 not to be retaken until the First Crusades in 1098 by French forces under command of Baldwin of Boulogne, who would later become King Baldwin I of Jerusalem.
Edessa, a high walled town along a major trade route seemed to be on the contested frontier of every empire that ruled it and thus it saw centuries of conflict in which it was sometimes conquered, sometimes successfully defended and sometimes ceded to victorious armies as part of a negotiated deal. As such it developed a varied culture of different peoples from many lands. When it became a Christian city is not clear, but it was so by the time it became part of the Byzantine. By 944, a date that will be very important in our analysis, it was under the jurisdiction of a Muslim Caliph but it retained significant communities of Greek Orthodox and Assyrians Christians as well as a number of Roman Catholics and possibly some Nestorians.