In the course of time there were other families of Kohanim in Israel, but for centuries the only family who served in the Temple and of whose numbers only one in each generation served as Kohen Gadol, was a member of the family of Zadok, the priest appointed by King Solomon. One can assume that the descendants of Zadok were the Kohanim who controlled the High Priesthood and the Temple service from the days of King Solomon, in 950 until the Maccabean Rebellion, when Judah became High Priest in 161 and Simon of the Hasmonean family assumed the supreme position around 155.
In fact, from the destruction of the Temple by the Babylonians in 586 B.C.E.until its rebuilding and restoration around 500, members of the family of Zadok were always held to be the legitimate claimants to the position of High Priest when the Temple would be restored. Therefore one could claim that the priesthood of the Zadokites, the family of the descendants of Zadok were in truth the legitimate Kohanim, one of whom should hold the position of High Priest in the Temple in Jerusalem.
If we are to date the period of the tenure of the position from the time of Zadok's appointment in 950 to the ouster of their Hellenizing descendants and the assumption of the Supreme Priesthood by Judah Maccabee in 161, we are dealing with a legitimacy of priesthood which continued for close to eight hundred years. After all, Shimon Ha-Tzaddik, one of the last members of the Knesset Ha-Gedolah, was a descendant of Tzadok and served as Kohen Gadol in Israel at a significant moment in the history of our people. That tenure of close to eight hundred years is a very strong claim to legitimacy. And this is one of the claims put forth by the Tzedukim, transliterated in Greek as Saddukoi that they are, in truth, the legitimate priests of the People of Israel.
But the Zadokite priests of the Antiochean persecution who were willing to compromise their Judaism and to submerge it under the Hellenic Paganism demanded by the foreign emperor who was the avowed enemy of Judaism, had compromised themselves out of traditional Judaism and betrayed their own heritage and the trust placed in them as the Kohanim of the Jewish People. Once the Hasmoneans were victorious, the Zadokite priests were out of power and their influence had dwindled to the vanishing point. But they were not totally destroyed. They continued to live among the Jewish People and gradually to assume a position and an interpretation of Judaism which had, to a certain extent, an element of legitimacy as an alternative philosophy of Judaism.