State formation in Hausaland was on course in precolonial Nigeria in the context of geographical proximity, biosocial relations and cultural contiguities before the development was impeded by the Fulani overlords in the Usman Danfodio led jihad (1804-1817). During the jihad, the populations of the Hausa (Habe) states were spontaneously disaggregated and later, re-aggregated to establish a new state, the Sokoto Caliphate. This paper examines the nexus between pre-colonial state formation and social identity transformation along ethno-religious lines in Hausaland under the Sokoto Caliphate. It finds that a major outcome of precolonial state formation in Hausaland is the transformation of social identities along ethno-religious lines. The paper argues that the jihad was not only motivated by the need for religious purification but also as much by the quest for ‘power to make binding decisions and authoritative allocation of values in the society’ and to also ‘determine who gets what, when and how’. This paper contends that the jihadists’ interception of the evolution of the Hausa States had two significant implications. Firstly, it ended the possibility of the transformation of the Hausa States under the Habe rulers into an empire and aborted the Habe dynasties while enthroning the rule of the Fulani over states in Hausaland. Secondly, the Hausa states founded on the cosmopolitanism ideology were transformed to adopt a new ethno-religious identity, the Hausa-Fulani. These implications were to significantly influence the trajectories of social identity formation in Hausaland under the Caliphate.