 The Arab – Khazar wars were a series of conflicts fought between the armies of the Khazar Khaganate and the Umayyad Caliphate ( as well as its Abbasid successor ) and their respective vassals . Historians usually distinguish two major periods of conflict , the First ( сa . 642 – 652 ) and Second ( ca . 722 – 737 ) Arab – Khazar Wars , but the Arab – Khazar military confrontation involved several sporadic raids and isolated clashes as well , over a period from the middle of the 7th century to the end of the 8th century . 
