have wider influence than other traders. While slave-raiding had been practised by Southern warlords before, the trade was taken under Zubeir to unprecedented large-scale levels. According to another pioneer of Sudan academia, Richard Gray, "by 1867 it was reliably estimated that 1800 slaves a year were being despatched northwards by Zubair". It is widely assumed that in what is now South Sudan altogether as many as 400,000 people were enslaved in just fourteen years. Many thousands are also assumed to have been killed as they resisted. Deim Zubeir became "the metropolis and the clearing house of the slave industry in that part of the world." Zubeir himself later claimed in a number of interviews that the establishment of his rule was a civilising mission in the name of Islam and that locals flocked to him for life service because of the stable conditions he provided in contrast to their previous poverty and insecurity. He also argued that European colonialism in the name of abolitionism was just another form of slavery. In 1871, at the height of his power, when Zubeir controlled much of the Bahr el Ghazal region as well as what are today parts of Chad and the Central African Republic, he was visited at Deim Zubeir by the pioneering botanist and ethnologist Georg Schweinfurth, who was the first European to see the place. A blog series by the Smithsonian Libraries summarises the impressions of the Baltic German scholar and abolitionist, who went on to become a leading proponent for colonial ambitions of the German Empire, as follows:"He found it to be a small town of many thousands of people, including Zubayr's army, government officials, and traders and their armies, all with their wives, concubines, children, personal slaves and their families, plus a group of religious authorities (ulema). To survive, this parasitic community raided surrounding villages, stealing cattle and food crops and taking slaves not only for service in the zariba but also to work the traders' own farms back in northern Sudan and, of course, to sell to foreign markets. Schweinfurth reported seeing four classes of slaves, all subjected to 'unbelievable degradation and cruelty': adult men, who served as soldiers; boys ages seven to ten, who carried their guns and ammunition; women, 'passed like dollars from hand to hand' as wives, concubines, and household servants; and both men and women to do field work and care for animals.