We really don’t have an unbiased source for anything of the time - not about the Pharisees, Saducees, Essenes, etc. etc.
“History,” even the thinly-veiled unbiased history books we have now, did not exists until much later. Josephus writes from his point of view, the Jewish writers their’s, Christians their’s and so on for all the “history” we have of these times.
So, if we’re going to require extra-biblical, extra-Christian, extra-judaism, objective history, we really have nothing. So, “what we know” has to either be nothing or be based on the sources we have with whatever conditions and scholarship, archeology, etc. that we can apply.
Archaeological evidence disputes Biblical evidence of Egyptian exile and Exodus, and for that matter most of Biblical history. Lack of evidence does not permit assuming a biased story is true. It doesn't have to be false, but cannot be treated as true, therefore questionable.