This demarcation was reinforced by internal convulsions within the Moslem world culminating in the accession of the Abbasid Caliphate (750), which moved the Islamic capital from Damascus to Baghdad.

• 这一分界线因穆斯林世界的内部骚动而得以加强，阿拨斯王朝的建立（750年），伊斯兰教首教从大马士革迁移巴格达，结束了这种骚动。