Students of medieval Arabic Islamic history have available for use an extensive array of Arabic medieval sources: historical and biographical sources, collections of the Prophet Muhmmad's Tradition Hadith, belles-lettres adab (poetry and prose), religious and ethical writings, geographical, and a variety of other materials. The richness of the medieval Arabic sources, which is at times intimidating, severely tests the capability of the students of this history to use this vast resource. These students should be envied not only for this richness, but also for the abundance of modern scholarship discussing these sources in particular, and Arabic historical thought in general. The problem, however, is not the availability of the material, rather in reading it in a way that contradicts clear evidence in the sources. The danger in reading the sources wrong for once will result in reading all related issues. A good example for this is the characterization of the army of the Abbasid caliph al-Mu‘tasim (833-42). For the last half century, and up till now, al-Mu‘tasim and his reign are connected with military slavery, changing the balance of power in the Islamic Caliphate in favor of the Turks. This paper, argues that such reading for the sources is at best inaccurate. This will be demonstrated by analyzing texts related to the establishment of the city of Samarra’, the two terms ghulam and istana‘a on which the above reading is built. In arguing the establishment of Samarra’, a comparison, the first of its kind between Kufa, the garrison established by the second Caliph ‘Umar b. al-Khattab, and Samarra’, will prove that Samarra’ was not a new system in establishing cities or garrisons. As for the terms of ghulam and istana‘a, the paper will present different types of texts using these terms to demonstrate that they were not used at the time as indicating the meaning of “slave” for ghulam or “training slave soldiers” for istana‘a. The discussion will include a table on the use of these terms in Early and Medieval Arabic sources. This table shows that none of the sources consulted refers to ghulam as a trained slave soldier. The paper demonstrates, and thus concludes that the role of slaves has been misread and overstated, and that the sources do not support the assumption that the Islamic State during the time of al-Mu‘tasim was run by slaves.