This year, 2017, marks 70 years since the discovery of the famous Dead Sea Scrolls at Khirbet Qumran by the Dead Sea in 1947. The Dead Sea Scrolls are one of the most well-known archaeological discoveries of the 20th century. This book addresses the proto-history and the roots of the Qumran community and of the Dead Sea Scrolls in the light of contemporary scholarship in Alexandria, Egypt. Alexandria, as the centre for Hellenistic Jews and the location of the Library of Alexandria, forms a key to understanding the theme of the book. The relationship of this context to the thoughts of the Essenes, the Jewish philosopher Philo of Alexandria, the Jewish Therapeutae of Egypt living in the neighbourhood of Alexandria and the Pythagoreans are especially studied in this work. Historical sources (both Jewish and Classical authors) and archaeological evidence are taken into account in the wider Graeco-Roman context. The connection between the Jewish Therapeutae in the Lake Mareotis region and the Palestinian Essenes is explained by the 'Jewish Pythagoras' based on the idea that the movements share the same philosophical tradition based on Judaism and Pythagoreanism. The prototypes of the Dead Sea Scrolls are explained in their Egyptian context, in association with the Library of Alexandria, the Egyptian temple manuals, and the formation of libraries in the Hellenistic period including that of Qumran.