 In return for iqtaʿat , annual customary payments , and honorary titles and robes , the amir al @-@ ʿarab was expected to command his horsemen as auxiliaries in the wars against the Mongols , the Crusaders , their allies and rebellious Mamluk emirs . Another expectation of the amir al @-@ ʿarab and the lower @-@ ranking tribal chieftains was intelligence gathering regarding enemy movements near the frontier . Among the official duties of the amir al @-@ ʿarab and the Syrian Bedouin tribes was the defense of the sultanate 's boundaries , and maintenance and oversight of the roads , bridges and mountain passes of the desert and within their iqtaʿat . This also entailed the protection of merchant travelers and the annual Hajj pilgrim caravan , which traversed Bedouin territory to reach the Muslim holy cities of Mecca and Medina in the Hejaz . Tribesmen also served as desert guides for the army and state officials . The amir al @-@ ʿarab was further responsible for collecting zakat ( dues ) on the livestock of the Bedouin tribes . 
