Tribes are often seen as territorial, pugnacious, and collectivized. In fact, they are quite resilient, individualistic, and readily accepting of others’ practices. When one turns to the law, we can see these features at work in the Berber and Arab tribes of the Middle East, both currently and historically. By starting with the practices of the Berbers of North Africa and then comparing the features they exhibit in their customary law – both substantive and (more importantly) procedural – the similarities to Islamic law are striking. Moreover, it is suggested, this is not surprising, as much of the procedural aspects of classical and modern Islamic law developed out of the tribal background of the Prophet’s day and finds additional support in the precepts of sacred texts. Thus, the comparison of Berber tribal law and Islamic law underscores the continuity of Islamic law, one reasons why it could spread into diverse regions of the Middle East and North Africa so quickly, and why we need to see the spread of Islam not simply as having been carried by military conquest and economic contact but by a form of law that readily resonated with the tribes the new religion encountered.