Using little-known real history can be very narratively risky, as people may be much more familiar with what they think is historically true but actually isn't, and assume the writer is wrong.

This seems to come up with particular frequency regarding sexuality, the roles of women, and technology, and I remember a number of discussions in rasfw in which one person would say something like, "And then in a totally politically correct touch, he brought in a Chinese woman leading a pirate fleet, like that could have ever happened, and I threw the book against the wall," and someone would reply, "But Mrs. Cheng was a real person."