Musically, "Rockers" refers to a specific subgenre and production style of roots reggae that dominated Jamaica roughly between 1975 and 1979.
The Sound: Pioneered by drummers like Sly Dunbar (with the Revolutionaries at Channel One Studio) and key artists like Augustus Pablo, the Rockers style replaced the older, laid-back "One Drop" groove with a heavier, more complex, and "militant" drum rhythm.
"Original Rockers": Describes the authentic, unadulterated tracks, riddims, and musicians from that golden era of 1970s roots reggae, distinguishing them from later dancehall or digital adaptations.
In Jamaican Patois, calling someone an "Original Rocker" (or referring to a group as "Rockers") refers to the street-smart, conscious, and stylish individuals tied to the Rastafarian sound system culture.
The phrase is closely associated with the iconic 1978 Jamaican reggae film Rockers, directed by Theodoros Bafaloukos. Starring drummer Leroy "Horsemouth" Wallace and featuring legendary musicians like Burning Spear, Gregory Isaacs, Jacob Miller, and Robbie Shakespeare playing themselves, the movie showcased authentic ghetto life, sound system culture, and Rasta philosophy in Kingston.