Last month, the twenty-two-year-old Jamaican singer and rapper Koffee appeared as a musical guest on the “Tonight Show.” The studio’s stage had been outfitted to look like a casual and haphazard dance ...

One reggae fan clad in Army fatigues squatted near the speakers, crouching and straightening as if on a trampoline. Musicians, promoters and radio hosts clustered around tables. By the end of the ...