Under Abd al-Malik, loyalist Syrian troops began to be deployed throughout the Caliphate to keep order, which came largely at the expense of the tribal nobility of Iraq. The latter's revolt under Ibn al-Ash'ath demonstrated to Abd al-Malik the unreliability of the Iraqi "muqātila" in securing the central government's interests in the province and its eastern dependencies. It was following the revolt's suppression that the military became primarily composed of the Syrian army. Consecrating this transformation was a fundamental change to the system of military pay, whereby salaries were restricted to those in active service. This marked an end to the system established by Caliph Umar (), which paid stipends to veterans of the earlier Muslim conquests and their descendants. While the Iraqi tribal nobility viewed the stipends as their traditional right, al-Hajjaj viewed them as a handicap restricting his and Abd al-Malik's executive authority and financial ability to reward loyalists in the army. Stipends were similarly stopped to the inhabitants of the Hejaz, including the Quraysh. Thus, a professional army was established during Abd al-Malik's reign whose salaries derived from tax proceeds. The dependence on the Syrian army of his successors, especially Hisham (), scattered the army among the Caliphate's multiple and isolated war fronts, most of them distant from Syria. The growing strain and heavy losses inflicted on the Syrians by the Caliphate's external enemies and increasing factional divisions within the army contributed to the weakening and downfall of Umayyad rule in 750.