These three categories are the most important pillars of Ibn Khaldūn's theoretical reconstruction of the patrimonial empires of the steppe; they are closely interconnected, and change in any one is accompanied by change in the other two. The confusing variety in Ibn Khaldūn research is most apparent in the interpretation of these concepts, which results as much from the subjective attitudes of researchers and their knowledge as from Ibn Khaldūn's slightly erratic use of the categories, because he makes a continual attempt to assess the complex change of function of constantly varying actors in an ever-changing historical variation. cAsabiyya especially, Ibn Khaldūn's real trouvaille, perhaps his most important category, mostly falls victim to anachronistic, modernising interpretations.1 What makes the category hard to grasp is that semantic content links the patriarchal tribal nature of cumrān badawī to the patrimonial imperial nature of cumrān hadharī. The problem is therefore that, given an invariable (that which cements the patriarchal tribal nature, its driving power and the bearer of its dynamism), the irrational force that cements the patriarchal community and endeavours by legal means to surpass itself and to impose itself on settled communities etc. by conquest, the newly created formation ("urban civilisation") tries at one point to neutralise this casabiyya and to organise itself in accordance with some new principle of integration, lack of that leads to the collapse of the given historical formation, and a new cycle begins with a further wave of conquest. That is to say, up to a point the motive force of the entire form of movement (i.e. casabiyya) is indispensable and plays a positive role, but then begins to play a negative role when those able to exercise dynastic power try to replace the old blood-linked retinue, which has become cumbersome, by servants that are loyal to them. The paradox of this historical movement is that within three generations the "urban civilisation" that takes shape, the patrimonial empire of the steppes created through the dynamism of casabiyya, puts an end in such a way to the cementing force that had created it (irrational group solidarity) that it can create nothing else to take its place. This brilliant realisation and convincing analysis mean at the same time that Ibn Khaldūn judged the umma, governed by ijmac, to be unsuitable for the exercise of political power. He regarded only casabiyya as a force that formed and maintained groups and determined the essential features of the character and functioning of a given societal organisation: the question of hegemony,2 the problem of the stratification of society,3 the legitimation of the exercise of power and the principle behind the establishment of institutions.4