Son of the Sudanese leader Muhammad Ahmad ibn Abd Allah, “the Mahdi”. Regrouped his father's followers, the Mahdists, as a religious order in 1908. Built the family's mosque in Omdurman and cultivated lands on Aba Island, where the Mahdi had announced his mission in 1881. These actions enabled Abd al-Rahman to proclaim the imamate of Ansar and create a spiritual, political, and economic center for the movement on Aba. He was the patron of nationalists advocating a separate independent Sudan not united with Egypt. He established the Ummah Party in 1945.