The Straight Dope has a reprint of a 1982 column that purported to be a primer on S&M.
S&M has been around for thousands of years; the Roman historian Tacitus is said to have made reference to it, and I suppose most of the basic gear involved traces back about as far. But many props are of fairly recent origin, notably motorcycle paraphernalia. You can also get something called a “Vietnamese basket” to hang your partner from the ceiling with–one of many legacies of the late war.
In addition, many of the rituals, particularly the fantasies indulged in by heterosexuals, are inspired by relatively recent events. “Prisoner and concentration camp guard” is unfailingly popular. In Victorian England there grew up an elaborate ritual involving “governesses” who disciplined erring “students” with the birch rods then in general use in the public schools.
This is the kind of sketchy analysis I hope to replace with real historical scholarship.
(Thanks to anothervu on Fetlife for posting this link.)