Saracen ( ) was a term used in the early centuries, both in Greek and Latin writings, to refer to the people who lived in and near what was designated by the Romans as Arabia Petraea and Arabia Deserta. The term's meaning evolved during its history of usage. During the Early Middle Ages, the term came to be associated with the tribes of Arabia. The oldest known source mentioning "Saracens" in relation to Islam dates back to the 7th century, in the Greek-language Christian tract Doctrina Jacobi. Among other major events, the tract discusses the Muslim conquest of the Levant, which occurred after the rise of the Rashidun Caliphate following the death of the Islamic prophet Muhammad. The Roman Catholic Church and European Christian leaders used the term during the Middle Ages to refer to Muslims—usually Arabs, Turks, and Iranians. By the 12th century, "Saracen" had become synonymous with "Muslim" in Medieval Latin literature. Such an expansion in the meaning of the term had begun centuries earlier among the Byzantine Greeks, as evidenced in documents from the 8th century. Before the 16th century, "Saracen" was commonly used in Western languages to refer to Arab Muslims, and the terms "Muslim" and "Islam" were generally not used, with a few isolated exceptions. The term gradually became obsolete following the Age of Discovery. Early usage and origins The Latin term Saraceni is of unknown original meaning. There are claims of it being derived from the Semitic triliteral root šrq "east" and šrkt "tribe, confederation". Another possible Semitic root is srq "to steal, rob, thief", more specifically from the noun sāriq (), pl. sāriqīn (), which means "thief, marauder". In his Levantine Diary, covering the years 1699–1740, the Damascene writer Hamad bin Kanan al-Salhi () used the term sarkan to mean "travel on a military mission" from the Near East to parts of Southern Europe which were under Ottoman Empire rule, particularly Cyprus and Rhodes. Ptolemy's 2nd-century work, Geography, describes Sarakēnḗ () as a region in the northern Sinai Peninsula. Ptolemy also mentions a people called the Sarakēnoí () living in the northwestern Arabian Peninsula (near neighbor to the Sinai). Eusebius in his Ecclesiastical history narrates an account wherein Pope Dionysius of Alexandria mentions Saracens in a letter while describing the persecution of Christians by the Roman emperor Decius: "Many were, in the Arabian mountain, enslaved by the barbarous 'sarkenoi'." The Augustan History also