The main purpose of this paper is to identify, study, and evaluate the early sources of the English historian Edward Gibbon, about Muslims in his work the History of the Decline and Fall of the Roman Empire. Gibbon’s treatment of Islam has not been studied to great extend. From the initial study of Gibbon’s work, one can categorize Gibbon’s treatment of Islam as a turning point in how the historians of the Protestant World in Early modern Europe viewed the Orient in general and the history of Muslims in particular. Traditionally, Byzantine historians were the main sources of Islamic history. Gibbon was critical of the Greek historians. In his views the Greeks, so loquacious in controversy, have not been anxious to celebrate the triumphs of their enemies. Therefore, Gibbon looked for other venues preferably to be early sources of Islam. The main goal of this paper is to examine these sources and evaluate them and to demonstrate to what extent of reliability and how much validity these sources for the early history of Islam were. Gibbon mentions four sources represent the annals, which have guided him in this general narrative 1- Annales Eutychii, Patriarchae Alexandrini, 2- Historia Saracenica of Georgii Elmacini,known as Elmacin or al-Makin, 3- Abulphargio, 4- Abulfeda Annales Moslemici Needless to say that he obtains his information about Muslims from the Latin translations of these sources. A quick look of evaluation of these sources, one can say that the best of Gibbon’s Chronicles, both for the original and version, yet how far below the name of Abulfeda. We know that he wrote at Hamah, in the 14th century. The three former were Christians of the 10th 11th and 13th centuries, the two first, natives of Egypt, a Melchite patriarch, and a Jacobite scribe. This study is of great significance in the field of Islamic historiography in early modern Europe. It shades some lights on the place of Islam in important history works in Europe such as that of Gibbon. Gibbon was one of early modern Europe historians who laid the foundations of the laws of history criticism, therefore, it would be worthwhile attempting to study how Gibbon influenced later generations of European historians on their treatments of Islam.