The first plague pandemic was the first historically recorded Old World pandemic of plague, the contagious disease caused by the bacterium Yersinia pestis. Also called the early medieval pandemic, it began with the Plague of Justinian in 541 and continued until 750 or 767; at least fifteen or eighteen major waves of plague following the Justinianic plague have been identified from historical records. The pandemic affected the Mediterranean Basin most severely and most frequently, but also infected the Near East and Northern Europe, and potentially East Asia as well. The Roman emperor Justinian I's name is sometimes applied to the whole series of plague epidemics in late Antiquity, as well as to the Plague of Justinian which struck the Eastern Roman Empire in the early 540s. The pandemic is best known from its first and last outbreaks: the Justinianic Plague of 541549, described by the contemporary Roman historian Procopius, and the late 8th century plague of Naples described by Neapolitan historian John the Deacon in the following century (distinct from the much later Naples Plague). Other accounts from contemporaries of the pandemic are included in the texts of Evagrius Scholasticus, John of Ephesus, Gregory of Tours, Paul the Deacon, and Theophanes the Confessor; most seem to have believed plague was a divine punishment for human misdeeds. While Latin and Byzantine Greek texts treated the disease as a generic pestilence (λοιμός, plaga), only later did Arabic writers term the condition ṭāʿūn (to some extent interchangeable with wabāʾ, 'plague'). In Syriac, both bubonic plague and the buboes themselves are called sharʿūṭā. The Chronicle of Seert makes this term synonymous with Arabic ṭāʿūn. Often, however, Syriac writers referred to an outbreak simply as a pestilence or mortality, mawtānā, equivalent to Arabic wabāʾ. In Pseudo-Zacharias Rhetor's Historia Miscellanea, the clarifying combined form mawtānā d sharʿūṭā (plague of tumors) is found. The Chronicle of 640 of Thomas the Presbyter dates the "first plague" (mawtānā qadmayā) to the year AG 854 (AD 542/3).