The Oxford University Press has an annoying post for Women’s Day that claims to be a timeline for “Landmark Moments for Women in Philosophy.” They weren’t really even trying. For Oxford, the earliest woman philosopher they came up with was Elena Cornaro Episcopia who was awarded a Phd. in 1678. So what they really mean is women who are eligible for the tenure track! They skipped the Ancient World all together from Hypatia to Hildegard of Bingen, and never mind anyone from East. There is a more complete list at Wikipedia: https://en.wikipedia.org/wiki/List_of_women_philosophers
Happy Women’s Day indeed!