The forgotten war that defined the borders of the medieval Islamic world
Between 642 and 799, Arab caliphates and the Khazar Khaganate fought a brutal, centuries-long struggle for control of the Caucasus. This clash of civilizations, driven by expansionist zeal and nomadic defense, reshaped the map of the Near East and ultimately helped trigger the collapse of the mighty Umayyad dynasty.
The Arab–Khazar wars were not merely a series of border skirmishes but a fundamental collision between the expansionist Umayyad Caliphate and the semi-nomadic Khazar Khaganate. For the Arabs, the conflict was an ideological imperative, a manifestation of jihad aimed at securing the Caucasus as a northern frontier. For the Khazars, the war was a defensive necessity, a fight to protect their steppe homeland from a settled power that viewed them as the mythical, apocalyptic hordes of Gog and Magog.
The conflict reached its peak in the eighth century, characterized by massive expeditions and decisive battles like the 730 engagement at Ardabil. The Arabs, utilizing professional Syrian troops and superior logistics, eventually established Derbent as a permanent military outpost. However, the Khazars' lack of a fixed administrative center made them difficult to subdue, as they simply retreated into the Volga Delta when pressed. The intensity of this warfare drained the Umayyad military, creating internal instability that culminated in the 750 Abbasid Revolution.
By the late eighth century, the conflict subsided into a period of relative peace, transforming the Caucasus into a vital trade artery between the Middle East and Eastern Europe. While the Khazars remained a power until the 10th century, the era of large-scale, existential warfare ended in 737. The legacy of these wars persists in the historical memory of the region, where the strategic importance of the Caucasus passes has been a constant concern for imperial powers since antiquity.
Source: Arab–Khazar wars
