How did steam transportation and print culture reshape the Ottoman Empire's centre-periphery relations in the nineteenth century? Challenging the Caliphate offers a fresh perspective on modernization in the Muslim world, exploring how these developments in infrastructure, technology, and communications impacted ideas of the Caliphate, Wahhabism, and Mahdism. Through rich archival research and microhistorical examples, Ömer Koçyigit demonstrates how new technologies influenced political authority, religious movements, and the spread of ideas. Koçyigit further explores how the Ottoman Empire dealt with the rise of the Wahhabi movement in the Najd and the Mahdi movement in Sudan. This study situates the Ottoman experience within global transformations, offering a deeper understanding of state, resistance, and connectivity while highlighting how emerging technologies shaped the modern Muslim world.