BDSM as a subculture and a lifeway with a more or less continuous history dates to the emergence of the earliest stages of the Leather subculture following WWII. In this context, it was part of the gay cultural sphere. There are many cases of the portrayal of BDSM activities prior to that period, of course. But they are not part of any continuous cultural phenomenon, beyond the phenomenon of human sexuality. Things really get off the ground, as far as the subculture goes, around the time of The Story of O, in 1954. This is significant for a few reasons. It's written by a woman. It portrays a 'society' of BDSM practitioners. And it becomes an inspiration for others who organise real world BDSM groups. It is also contemporaneous to the emergence of the Leather culture earlier mentioned, so it is a rare opportunity to give heterosexual expression to something akin to Leather's ideas and practices, and in particular to focus on the notion of assuming a slave or submissive role or lifestyle, rather than merely to focus on sadomasochistic acts as a sexual practice (which are otherwise much more well attested).

It is in the Internet era that heterosexual BDSM has really gotten off the ground, though, as a well-defined movement with well-defined practices (like play parties, and munches). Some old-timers like to tell stories about the good old bad old days, of calling ads for personals lines in the back of kinky porn mags. But the scale of those activities and the scope of their creative and social expression as a community building exercise was necessarily limited.

I am not, by any sort of dedicated practice, a BDSM historian. Hence the informality of this history. But I am a long time member of both the gay and straight sides of the community (and so have exposure to both sides of its history), and moderate /r/bdsmpersonals and /r/bdsmerotica. My wife is currently kneeling at my feet (as she often does, when I'm at the computer), with a titanium collar around her neck. So this is not just an interest, for me, but also an important part of my reality.