An influential view holds that the Arab tribal system found in the works of the classical genealogists was created through the actions of the Umayyad government to administer the tribal populations of the garrison towns of southern Iraq. This view, however, inadequately addresses the administrative mechanisms through which state power was articulated and the social logic through which it was rationalized. In addition, several arguments used to initially construct this argument in Patricia Crone's Slaves on Horses have grown much weaker with age. Crone presupposes a lack of state structures in Arabia prior to Islam, which is now untenable. She also argues from the case of the Mongols as a perceived paradigm for all nomadic conquerors, when advances in ethnography suggest strong differences across different pastoral nomadic societies, particularly between Central Asia and the Arab world. Furthermore, David Sneath has recently consolidated the threads of a paradigm shift within Central Asian Studies which demolishes the tribe/state dichotomy on which the imported model is based. With this background, and noting other evidence from Basra and Kufa which does not seem to comport with current views, I propose an updated version of developments within the Arab tribal system produced through a dynamic interaction between the authorities of the caliphal government and tribesmen migrating from the Arabian Peninsula. Using the case of al-Azd in Basra, I call attention to the ways aspects of desert Arabian society, such as the hilf hosting alliances, were used by locals and newcomers to develop the alliances which composed the al-Azd conglomerate during the Sufyanid period. Information concerning the B. 'Imran cluster of al-Azd from events of the Sufyanid period combines with the genealogical accounts to shed light on the ways the latter might have been constructed out of the different groups. A consistent theme is that what happened in the garrison towns was in part the activation and ultimate privileging of particular levels of identity, a process similar to one noted by Shelagh Weir during the Hamid al-Din period of Yemen.