No idea's original. Hip-hop is a 39-year-old musical genre, and at this globalized stage of its evolution, we can trace the appeal of so many contemporary rappers back to a few, crucial wellsprings of inspiration. With hi-speed Internet having demolished regional boundaries and stylistic distinctions, at least within the U.S., influences migrate with the quickness. Atlanta trap star Gucci Mane is a patron saint of Chicago's drill scene. Drake is Lil Wayne's protégé and a huge UGK stan. Nicki Minaj, despite her abundance of unique quirk, occasionally channels the Notorious B.I.G. ("Four Door Aventador") and KRS-One ("Monster"). Danny Brown, from Detroit, cites UK grime godfather Dizzee Rascal as his definitive role model.

Even the very best contemporary rappers are, for the most part, elevating the style and ideas of generations that preceded them. Here we take a look at 20 rappers who are influencing the rest of contemporary hip-hop.