Aba Island was the birthplace of the Mahdiyya, first declared on June 29, 1881 as a religious movement by Muhammad Ahmad, the self-proclaimed Mahdi.

Many of them identified 'Abd al-Rahman with the Islamic prophet Isa (Jesus) and assumed that he would drive the Christian colonists out of Sudan.

[1] The British found that the Abd al-Rahman al-Mahdi was in correspondence with agents and leaders in Nigeria and Cameroon, predicting the eventual victory of the Mahdists over the Christians.

After pilgrims from West Africa held mass demonstrations on Aba Island in 1924, Abd al-Rahman al-Mahdi was told to put a stop to the pilgrimages.

About 12,000 Ansar were killed in the assault including the uncle of Sadiq al-Mahdi and the extensive holdings and property of the Mahdi family were sequestered by the state.