The Essenes

The Essenes are not mentioned in the New Testament, or the Talmud, but they are well known in other sources like Philo, Josephus, and the elder Pliny. The Essenes have been described as " primarily nothing but a more emphatic Pharisaism." In the time of our Lord, there were apparently only about 4,000 of them. Bible History Online.

Link: https://bible-history.com/jesus/the-essenes