Jihad over Centuries
This paper investigates the origins of Islamist insurgencies as a form of cultural revival in West Africa. Exploiting variation in access to ancient water sources, which have largely disappeared, as an instrument, we show that the decline of trans-Saharan cities -- once-prosperous under pre-colonial Islamic states -- led to contemporary hotspots of Islamist violence. Contemporary violence is concentrated not where colonial resistance by Islamic states was fiercest, but where overwhelming military asymmetries induced outward submission, a pattern supported by historical evidence on weapon access. This strategic adaptation allowed radical Islamism to survive defeat and persist as a latent legacy. Qualitative evidence suggests ideological transmission was sustained through a religious practice of internally preparing to reassert Islamic purity. This mechanism is further supported by a dynamic model of conflict and individual-level surveys examining extreme religious ideologies. Moreover, the concentration of Islamist violence in areas that experienced reversals of fortune mirrors a global pattern.