Al-Zubeir Rahman Mansur was a businessman who established a large personal empire in central Africa. Setting out from Khartoum in 1856 with a small army of hired soldiers he set up a network of trading forts known as zeriba . This network eventually controlled the Bahr el Ghazal as well as some of what is today the Central African Republic and southern Chad. This network bought large quantities of ivory and slaves from the local inhabitants and shipped them north to Cairo.

After earlier conflict with the Egyptian government of the Sudan he was appointed governor of the Bahr el Ghazal in 1873 in return for an annual tribute of ivory. Zubeir's forces, on behest of the Egyptians, conquered the sultanate of Darfur in 1874. The arrival of Charles George Gordon as governor of the Sudan led to a campaign to suppress the slave trade upon which Zubayr's empire depended. Zubayr traveled to Cairo to complain, but once there was refused permission to return to his southern dominions. Widely acknowledged as a highly skilled military commander he elevated to a pasha and was instead sent to participate in the Russo-Turkish War of 1877.

His son Sulayman took over control of the Bahr el Ghazal. In 1878 Sulayman revolted against the Sudanese government and was defeated and executed by Romolo Gessi. In a controversial decision Gessi chose to execute Sulayman and the other leaders of the revolt.

Zubayr, while deeply angered by his son's death, but remained loyal. When the Mahdist revolt broke out Gordon asked for Zubayr's exile to be ended as he recognized that only he had the military skill and the connections in the region to defeat the uprising. Gordon's request was rejected as the British administrators felt it would be unpolitic to turn to the former slave trader for aid. Zubayr did raise a small force to fight the Mahdi.

The British, however, were worried about a possible alliance between Zubayr and the Mahdi and moved him from Cairo to Gibraltar in 1885 where he remained in exile there until 1899. In retirement Zubayr wrote his memoirs, which were translated into English as Black Ivory: Or, the Story of El Ziebeir Pasha, Slaver and Sultan, as Told By Himself.