His reputation as an archenemy of General Charles Gordon led to him gaining a near-mythic status in the United Kingdom, where he was referred to as "the richest and worst", a "Slaver King" "who [had] chained lions as part of his escort".

At its height, his trading empire, backed by a personal army, controlled much of the Bahr el Ghazal as well as what are today parts of Chad and the Central African Republic.

[6] That year, Gordon wrote back home "I have to contend with many vested interests, with fanaticism, with the abolition...with a large semi-independent province lately under Sebehr, the Black Pasha, at Bahr Gazelle".

[1] Prior to his 1878 departure to Cairo, where he intended to bribe other pashas with approximately £100,000 to recognize his sovereignty,[3] Rahma had gathered his chiefs under a tree between Shaka and Obeid where they agreed that if the plan failed, they would go "to arms!

Referring to him as a "cub", Gordon took an almost fatherly approach towards him,[1] and explained at his camp that he was aware of what revolts the slavers had been provoking, and he was now offering an ultimatum – either Suleiman announce his surrender of the Cave of Adullam or he would attack with an overwhelming force.

[1] Gordon wrote a few days later, "Suleiman no longer hopes to conquer...he may try to go up to other stations inland, but I do not expect it will last long; a retreating commander is rarely in a good temper, and he will soon disgust his people.

"[1] Angered, Suleiman rallied 6,000 of his men in large raids, which were quickly dispelled at Gordon's command by the troops of Yussuf Pasha and Romolo Gessi.

He accepted, but spent the following days again rejecting Suleiman's pleas for a title of government, but consoled the young chief by giving him a rifle and teaching him its proper use.

In March 1885, he was removed from command and imprisoned at Gibraltar, when British forces suspected that he might have negotiated fealty to Ahmad, the "false prophet", based on alleged correspondence between them.

In retirement Zubayr wrote his memoirs, which were translated into English as Black Ivory: Or, the Story of El Zubeir Pasha, Slaver and Sultan, as Told By Himself.