Saracens (/ˈsærəsən/) were primarily Arab Muslims, but also Turks or other Muslims as referred to by Christian writers in Europe during the Middle Ages. The term's meaning evolved during its history. In the early centuries of the Christian Era, Greek and Latin writings used the term to refer to the people who lived in desert areas in and near the Roman province of Arabia Petraea, and in Arabia Deserta. In Europe during the Early Middle Ages, the term came to be associated with tribes of Arabia. The oldest known source mentioning Saracens in relation to Islam dates to the 7th century. It was found in Doctrina Jacobi, a commentary that discussed the Muslim conquest of the Levant.