There are a couple of principles I keep in mind when studying history. The first is, “You have to work with the evidence you have.” We have no way of knowing how many people secretly had relationships like Arthur Munby and Hannah Cullwick, but left no historical evidence. Likewise, I and other scholars of this particular field have to contend with the lack of historical material about lesbian SM before the 1970s. Maybe somewhere there’s an old journal or manuscript or audiotape sitting in somebody’s basement, and someday somebody will find it and open up a new field of study.
The second principle is, “Absence of evidence is not evidence of absence.” It’s highly unlikely there were no lesbian women doing SM before 1974, but we can only make cautious, educated inferences based on what evidence we do have.
Thankfully, somebody scanned and posted old issues of Lesbian Tide, which contain what may be the earliest mentions of BDSM in lesbian media. As I mentioned before, lesbian SM emerged into visibility at the same time and in dialectic with more restrictive theorizations of lesbian-feminist sexuality, and it cannot be discussed without also discussing this conflict.