عبد الله التعايشي
In 1881, at the beginning of the Mahdist War, the Mahdi Muhammad Ahmad appointed Abdallahi ibn Muhammad as one of his four caliphs ("Khalifa") and handed him a black flag. Abdallahi used his black flag to recruit Baggara Arabs and other tribes from the west. The other caliphs used differently coloured flags. The black horizontal stripe in the current Sudanese flag is a reference to this Mahdist-era black flag.