The Ansar are a Sufi religious movement in the Sudan whose followers are disciples of Muhammad Ahmad, a Sudanese religious leader based on Aba Island who proclaimed himself Mahdi on 29 June 1881. His followers won a series of victories against the Egyptians, culminating in the capture of Khartoum in January 1885.

Sudan, officially the Republic of the Sudan, is a country in Northeast Africa. It borders the Central African Republic to the southwest, Chad to the west, Egypt to the north, Eritrea to the northeast, Ethiopia to the southeast, Libya to the northwest, South Sudan to the south, and the Red Sea. It has a population of 45.7 million people as of 2022 and occupies 1,886,068 square kilometres, making it Africa's third-largest country by area and the third-largest by area in the Arab League. It was the largest country by area in Africa and the Arab League until the secession of South Sudan in 2011; since then both titles have been held by Algeria. Its capital and most populous city is Khartoum.