 Wadi Sirhan was the home region from which the Salihids entered Syria and became the principal Arab federates of the Byzantine Empire throughout the 5th century CE.When the Salihids were succeeded by the Ghassanids at the beginning of the 6th century, Wadi Sirhan became dominated by the latter’s allies, the Banu Kalb.The Ghassanids were charged by the Byzantines with supervision over the region after Emperor Justinian dismantled the Limes Arabicus, a series of garrisoned fortifications guarding the empire’s eastern desert frontiers, .