inferior to these works. Adoption of Byzantine era The Byzantine Anno Mundi era was the official calendar of the Eastern Orthodox Church from c. AD 691 to 1728 in the Ecumenical Patriarchate. By the late 10th century the Byzantine era, which had become fixed at 1 September 5509 BC since at least the mid-7th century (differing by 16 years from the Alexandrian date, and by 2 years from the Chronicon Paschale), had become the widely accepted calendar by Chalcedonian Christianity. The Byzantine era was used as the civil calendar by the Byzantine Empire from AD 988 to 1453, and by Russia from c. AD 988 to 1700. The computation was derived from the Septuagint version of the Bible, and placed the date of creation at 5509 years before the Incarnation, which was later taken to mean 5509 BC when conversions to the Christian era were desired. With a new year date of September 1, which coincides with the beginning of the Orthodox liturgical year, its epoch became 1 September 5509 BC (Julian), and year AM 1 thus lasted until 31 August 5508 BC. The "year of creation" was generally expressed in Greek in the Byzantine calendar as Etos Kosmou, literally "year of the universe". Western church Western Christianity never fully adopted an Anno Mundi epoch system, and did not at first produce chronologies based on the Vulgate that were in contrast to the Eastern calculations from the Septuagint. Since the Vulgate was not completed until only a few years before the sack of Rome by the Goths, there was little time for such developments before the political upheavals that followed in the West. Whatever the reasons, the West eventually came to rely instead on the independently developed Anno Domini (AD) epoch system. AM dating did continue to be of interest for liturgical reasons; however, since it was of direct relevance to the calculation of the Nativity of Jesus (AM 5197–5199) and the Passion of Christ (AM 5228–5231). For example, Bede in his World-Chronicle (Chapter 66 of his De Temporum Ratione, On the Reckoning of Time), dated all events using an epoch he derived from the Vulgate which set the birth of Christ as AM 3952. In his Letter to Plegwin, Bede explained the difference between the two epochs. In popular culture In 1990, heavy metal band Black Sabbath wrote and recorded the song "Anno Mundi" for the opening track of