Muhammad Ahmad bin Abdullah bin Fahal was a Sudanese religious and political leader. In 1881, he claimed to be the Mahdi, and led a war against Ottoman-Egyptian rule in Sudan which culminated in a remarkable victory over the British in the Siege of Khartoum, while also slowing and defeating the British during their unsuccessful Nile Expedition to resupply the Khartoum Garrison. He created a vast Islamic state extending from the Red Sea to Central Africa, and founded a movement that remained influential in Sudan a century later.

Abdullah ibn-Mohammed al-Khalifa or Abdullah al-Khalifa or Abdallahi al-Khalifa, also known as "The Khalifa" was a Sudanese Ansar ruler who was one of the principal followers of Muhammad Ahmad. Ahmad claimed to be the Mahdi, building up a large following. After Ahmad's death, Abdullah ibn-Mohammed took over the movement, adopting the title of Khalifah al-Mahdi. He attempted to create a kingdom, which led to widespread discontent, and his eventual defeat and death at the hands of the British and Egyptians.