This essay's compares two millenarian jihadist state movements (the 21st century Islamic State and the 19th century Sudanese Mahdiyyah) and the security challenges they posed to the international order. It does so in three parts. First, it provides an overview of the apocalyptic component in Sunni Islam that guided these movements. Second, it assesses their leadership and ideology. Finally, it compares the defeat of the Mahdist state with the Islamic State's caliphate's collapse.