This work provides an understanding of the structure, the functioning and the mutation of tribes in the Middle East today. A contemporary view holds that modernity will inevitably lead to the extinction of pre-modern social organizations. However, the 1990s have shown that the tribal factor in some Middle Eastern countries has not only been strengthened but has become decisive. But tribes are not "passive" entities for they have a life of their own - they flexibly mutate, producing various new forms of tribalism in the process, and providing a platform for social, economic and political action. This platform has been allowed to expand and become more complex, despite the fact that authoritarian regimes have attempted to co-opt tribal configurations as a means of control and coercion. Nobility of lineage, tribal allegiance and other aspects of tribalism have been re-activated or re-structured to replace an eroded 'modern' revolutionary legitimacy. The theoretical part of this work scrutinizes the complexities of kinship structures in view of the Islamic and Arab culture; the case studies cover Iraq, Iran, Lybia, Morocco and Saudi Arabia.