The rappers hate the idea. The rockers, struggling with drugs and low record sales, don’t know what to make of Rubin’s pitch. But on a Sunday in March, they meet in a Manhattan recording studio to create what will become one of the most important songs of the modern pop era. This is the oral history of Run-D.M.C.’s cover of “Walk This Way.”

It’s Dec. 15, 1974, and Perry, Aerosmith’s 24-year-old lead guitarist, is messing with a riff before a gig in Honolulu. He asks drummer Joey Kramer to play along. Tyler, originally a drummer but now the band’s singer, jumps up when he hears the jam.

Joe Perry: I was really into the Meters, the esoteric, funky kind of music. Sly and the Family Stone. I started fooling around on this riff. I asked Joey to play basic, straight twos and fours. Like an AC/DC song. If I had a drum machine I would have done it. And Steven heard it and I think he came up onstage and . . . sat down at the drums and played something a little bit different than Joey was doing. I’m not sure.

Steven Tyler: He was up onstage doing sound check and he started playing that song and I ran out from the dressing room and started playing. I came up with it. Let’s just leave it at that. I’m a drummer at heart.

Joey Kramer: Basically, to the best of my recollection, I came up with it. I don’t remember anybody else being a part of it. It was a no-brainer. The drum lick kind of goes hand in hand with the guitar lick.