Judaism is clear on the matrilineal descent. Yet it's not clear to me that the Matriarchs after Sarah were "Jewish" - they were Abraham's relatives, they were not Canaanites as requested by Abraham, but were they followers of Hashem as Abraham, Eliezer, Isaac was? I'm not clear on this distinction of being "Jewish" vs. being a "Hebrew." Abraham is the first Jew, but the Jewish people do not "officially" exist until Sinai.
Same goes for Joseph's wife - I've been told she underwent a conversion, but if Judaism didn't necessarily exist, then how? What's the difference then between her and Isaac and Jacob's wives?
Bottom line: Were the matriarchs after Sarah explicitly Jewish?