Slam dancing started when punk rock music started. It is the original form of "moshing". Back in the mid 70's and in the 80's punk rockers slammed danced. There wasn't any hardcore violence involved. Ask anyone who actually lived through the era of punk rock and they will tell you the truth about slam dancing. "Moshing" is a new term for slam dancing but isn't slam dancing at all. Slam dancing basically consisted of jumpin around and not really doing any actual dance moves. It wasn't purposly violent dancing.
"Hey look at those scenester kids "moshing" and thinkin they are slam dancing."