4 SOCIAL SCIENTIST this hypothesis of Kosambi in greater detail elsewhere. *0 For our present purposes it is sufficient, to point out that although the assimilation of non-Aryan, aboriginal priests and ruling lineages as well as commoners into various varna categories is a process which has taken place throughout the ancient and medieval periods of Indian history, there is nothing to show that such assimilation had given rise to separate endogamous units or fatis within the various varna categories in the Vedic period. On the other hand, Kosambi rightly holds that the subjugation of the dasas and changes in the means and relations of production provided the material background for the emergence of the 'four castes' fully developed within the tribe: Brahmana, Ksatriya, Vaisya, Sudra, in Yajurvedic times and this was 'a new class division within each Aryan tribe5.** The description of varnas as 'castes' here is significant and shall have to be discussed later. Nevertheless, Kosambi's remarks on caste are not without ambiguity, which leads Irfan Habib to state that according to Kosambi 'castes did not arise out of any internal division of the varnas in the original Vedic society> but from an external process altogether', through the fusion of tribal elements into a general society. This assumes that in JKosambi's perception varnas were 'estates', 'order' or 'class' and not 'castes', a view contradicted by the passages quoted above. Habib adds-^ that tribes 'are often rigorously endogamous' and may have practised endogamy when they entered into the general society. But the question whether caste endogamy should be viewed as a continuation of tribal endogamous customs is far from settled. Scholars such as Max Weber^ and Louis Dumont^ have contrasted tribe and caste on the ground that the internal structure of the tribal world is exogamous and of caste society endogamous. In our opinion, Dumont's assertion that 'endogamy is a corollary of hierarchy, rather than a primary principle'* 5 of caste deserves serious consideration, of course, with the caveat that for us caste hierarchy is not just a religious principle but a system of exploitation of gender and weaker communities, l^ Kosambi held that caste is 'class at the primitive level of production'*' and originated in later Vedic times as varna divisions. However, sociologists generally make a clear distinction between the varna and jati regarding only the latter as castes and the former as 'estates' 'order' or status system'. This is done on the ground, that (a) varna are broad categories and the real effective social units today are castes; (b) varnas are only four but castes are numerous, (c) and whereas varna hierarchy is clear, there is a lack of clarity in the hierarchy of castes, particularly in the middle regions. However, this