The Banu Kalb was an Arab tribe which mainly dwelt in the desert and steppe of northwestern Arabia and central Syria. It was involved in the tribal politics of the Byzantine Empire's eastern frontiers, possibly as early as the 4th century. By the 6th century, the Kalb had largely adopted Christianity and came under the authority of the Ghassanids, leaders of the Byzantines' Arab allies. During the lifetime of the Islamic prophet Muhammad, a few of his close companions were Kalbites, most prominently Zayd ibn Haritha and Dihya, but the bulk of the tribe remained Christian at the time of Muhammad's death in 632. They began converting in large numbers when the Muslims made significant progress in the conquest of Byzantine Syria, in which the Kalb stayed neutral. As a massive nomadic tribe with considerable military experience, the Kalb was sought as a key ally by the Muslim state. The leading clans of the Kalb forged marital ties with the Umayyad family, and the tribe became the military foundation of the Syria-based Umayyad Caliphate (661–750) from the reign of Mu'awiya I to the early reign of Abd al-Malik.

The Umayyad Caliphate or Umayyad Empire was the second caliphate established after the death of the Islamic prophet Muhammad and was ruled by the Umayyad dynasty. Uthman ibn Affan, the third of the Rashidun caliphs, was also a member of the clan. The family established dynastic, hereditary rule with Mu'awiya I, the long-time governor of Greater Syria, who became caliph after the end of the First Fitna in 661. After Mu'awiya's death in 680, conflicts over the succession resulted in the Second Fitna, and power eventually fell to Marwan I, from another branch of the clan. Syria remained the Umayyads' main power base thereafter, with Damascus as their capital.