"I Enoch is a compilation of several separate works, most of which are apocalyptic. Its oldest portion is the “Apocalypse of Weeks,” written shortly before the Maccabean uprising of 167 BC against the Seleucids.
Other sections, especially those dealing with astronomical and cosmological speculations, are difficult to date. Because of its views on messianism, celibacy, and the fate of the soul after death, parts of I Enoch may have originated with or been influenced by the Essene community of Jews at Qumrān.
No fragments of the longest portion of the work (chapters 37–71), however, were found among the Qumrān writings. This has led scholars to theorize that this section was perhaps written in the 2nd century AD by a Jewish Christian who wished to imbue his own eschatological speculations with the authority of Enoch, and added his work to four older apocryphal Enoch writings.
I Enoch was at first accepted in the Christian Church but later excluded from the biblical canon.
Its survival is due to the fascination of marginal and heretical Christian groups, such as the Manichaeans, with its syncretic blending of Iranian, Greek, Chaldean, and Egyptian elements."
