They were freed annually. They were usually used in the service of their masters, and they remained as clients of the family. After the free men came the sons of slaves, who remained slaves and worked for their masters. They remained on the master's land and could not cultivate it or leave it without his permission. The wife of one of them was assigned as a slave to her master if she pleased him. On the other hand, the master could not sell them, and thus they were more like clients than slaves. Agriculture in Sudan was based on the labor of slaves, and the emperor had a large number of tribes with personal status. For example, Askia Muhammad the Great, after his victory over Sonni Ali, acquired twenty-four tribes. He freed ten of them based on the advice of Abd al-Rahman al-Suti. As for the remaining twelve tribes, they formed the basis of different classes engaged in forced labor. Another defect marred the Sudanese social organization, a defect stemming from the foundations it was built upon, as it lacked what could be called an ideology. The Sudanese state, with its administrative apparatus and its slave-based production methods, became, in one way or another, a predatory state. It was founded on the capture of slaves, and thus slaves and Islam entered into a continuous and prolonged conflict. It was not in the interest of the state's administration, nor in the interest of foreign merchants who lived off the slave trade, for Islam to spread in the ethnic regions. The conflict between Islam and paganism formed the roots of the fundamental problem in this part of the Islamic world. While the Islamic states advanced their religion, they undermined their trade, and indeed their entire social framework. On the other hand, their religion imposed upon them the guidance of the infidels. This problem was not resolved until the nineteenth century, when the trade...