The achievement of Ahmad ibn Idris was not the establishment of a single mass movement for revitalizing Islam. What he did accomplish was to lay the foundations for an important revivalist tradition in Islam. The Idrisi tradition gave birth to leaders of holy wars, men who established religious states, and a number of important centralized tariqahs. It was an important feature of the Islamic world in the nineteenth and early twentieth centuries. Its success was such that observers at the end of the nineteenth century felt that it was the source of much of the Islamic dynamism of the time. – John Voll
J.O. Voll, “A History of the Khatmiyyah Tariqah in the Sudan.” PhD. thesis, Harvard 1969, 103.