 Though its strategic value emanated from its role as a gateway for trans-Arabian trade and transportation, Wadi Sirhan was also a significant source of salt.At its northern end, it was guarded by the fortress of Azraq, while its southern end was guarded by the fortress of Dumat al-Jandal.At both forts inscriptions were found indicating the presence of troops from the Bosra-based Legio III Cyrenaica.