And the Essenes - depends on exactly how you cut your eras, of course.
It is really not that different from the Lutheran / Calvinist / Anabaptist deal, Puritans / Methodists / Quakers not so synchronous, the Transformationalist / Stratificationalist / Tagmemicist thing in 50s Linguistics, and a pile of other stuff.
There is a cycle. One group, with a specific style, comes to power and stays there. But people are not the same, so inevitably, in the best of circumstances, there are people want to see change, like the views that started to come out of the bushes when TG had been in power a while [which is why we had to have Son of Chomsky].
BUT since people are different, when they start to try to change stuff, these guys want to see it change THUS, these others want it SO. So when you get to - maybe not quite the same, but call it paradigm shift time - you will often get the stodgy mammoth splitting of two three four alternative successors.
Maybe eventually one wins, you start over.