Al Jazeera region from second half of the III. century to First Islamic Conquests

Human beings have established civilizations near the edges of water due to the favorable life conditions since ancient times. Our topic is the Al-Jazeera Region which locates between the Tigris and Euphrates Rivers, and it is called Mesopotamia by western people. Byzantine and Sassanids were the main ruler of the region in the III. and VII. centuries. The wars between these two states changed the balance of forces in the region and the border of the region changed many times.Harran, Edessa (Urfa), Batnae (Suruç), Hasankeyf, Amid and Nisibis (Nusaybin) form the East of Byzantine called East Rome and west borders of Sassanid. Cities such as Urfa and Nusaybin were also religious centers.Those two civilizations that is Byzantine and Sassanid, pursued different policies because their values and especially their religion were different. For example, while one of them supported belief of Nestorian, the other one was extremely negative to them.The situation of the region changed a lot because of the Islamic conquests and geographical terms had been the most significant example of this. The demographic structure also changed.As a result Sassanid and Byzantine exhausted each other by struggling so they gave in Islamic conquest easily.Key Words: Al Jazeera Region, Tigris and Euphrates Rivers, Mesopotamia, Byzantine, Sassanid, Border.