The Essenes איסיים

The main thing must be said at once: in Jewish tradition they do not appear. Neither the Mishnah nor the Talmud names them. All that is known comes from writers in Greek—Josephus and Philo of Alexandria—and from the Roman Pliny. For that reason alone the picture we have is an outsider's, and possibly shaped for a Greek reader.

By those accounts: they lived in communities, held property in common, were extremely strict in purity and in the Sabbath, and many did not marry. Admission was by stages and took years. They existed from the middle of the Second Temple period and vanished in the war with Rome.

And the Qumran question. Since the finding of the scrolls it has been widely held that the Qumran community was Essene: the community of property agrees, and the strictness of purity, and the seclusion. The view is common but not proved: the Qumran texts do not call themselves Essene, and there are scholars who read them otherwise. We call it a supposition, because that is what it is.

For Jewish history they matter not in themselves but for what they show: before the Temple's destruction the people were not uniform, and there were more than two ways of being a Jew.