How did former slave traders become supporters of the Mahdist movement?

Former slave traders became supporters of the Mahdist movement primarily due to the economic disruption caused by the government's efforts to abolish the slave trade.12

Under the administration of Charles George Gordon, who was appointed governor-general of the Sudan in 1877, the government aggressively enforced the Anglo-Egyptian Slave Trade Convention. This campaign involved breaking up slave markets and imprisoning traders, which severely damaged the economic standing of those involved in the trade.3

Consequently, these merchants joined the Mahdist movement in hopes of reasserting their economic position under the banner of a religious war against the existing government. While they were a powerful and numerous group within the Mahdī's following, they were one of several factions—alongside religious holy men and the Baqqārah nomads—that coalesced to challenge the Egyptian-Ottoman administration.12