Describes and integrates the contrasting histories of different parts of the empire. The Roman empire during the period framed by the accession of Septimus Severus in 193 and the rise of Diocletian in 284 has conventionally been regarded as one of 'crisis'. Between 235 and 284, at least eighteen men held the throne of the empire, for an average of less than three years, a reckoning which does not take into account all the relatives and lieutenants with whom those men shared power. Compared to the century between the accession of Nerva and the death of Commodus, this appears to be a period of near unintelligibility. The middle of the century also witnessed catastrophic, if temporary, ruptures in the territorial integrity of the empire.