A history of gender nonconformity, Before We Were Trans is an imperfect but important and sensitive look at how people have found and made space for themselves outside of the gender binary in various cultures and time periods. 

Kit Heyam is a trans author and makes it clear that they feel dissatisfied with the level of evidence required to say that people of the past were trans, so it is clear throughout that some conjecture is involved. Heyam does an excellent job of presenting factual information in a respectful way, even when people of the past were not treated with respect by their societies. One important lesson from the past is that perhaps we don't need to always separate gender from sexuality, many past societies saw them as connected and for many people, queer, trans, or cis, they are connected parts of identity. 

This book will let you consider all the ways our society is creating space and positive change but also ways we could view all people holistically, instead of piecemeal.