You don't have to be that old to remember when record retailers had a single category called "world music," where everything from Indian ragas to Irish jigs to Nigerian Afrobeat to Jamaican reggae was ghettoized in a sales bin far from the mainstream displays.

Well, turnabout is fair play. Nowadays it's the world's most creative, cutting-edge bands that are doing the mash-ups, creating self-contained global musical hybrids so organically interwoven that not even the most sophisticated categorizer could pigeonhole them. Last year's best example was the Brooklyn-based group TV on the Radio. Now comes South African quartet Blk Jks, whose postmodern polyglot of international styles makes them the perfect choice to open this week's Global Roots Festival at the Cedar Cultural Center.

"Growing up, we listened to everything: Salif Keita, Fela Kuti, Bob Marley, Frank Zappa, Curtis Mayfield," said drummer Tshepang Ramoba, as the other three band members called out other names -- "Smashing Pumpkins"! "Ladysmith Black Mambazo!" "Jimi Hendrix!" -- by phone from South Africa. All those influences and more are embedded to some degree in the songs on "After Robots," Blk Jks' first full-length recording.

The lead track, "Molalatladi," features African-style vocal chants a la Keita, sonorous horns like Kuti and guitar eruptions that split (shred?) the difference between Hendrix's wail and Zappa's crazy-quilt phrasing. By contrast, "Skeleton" is a quavering, seductive ballad with a reggae tempo laced with dub reverb and a healthy dash of Pink Floydian bombast. Other tracks boast the electronic layering and rubbery pop-rock of Radiohead, sweetened R&B that connects Curtis Mayfield and Ladysmith Black Mambazo, and the shape-shifting textures of drum 'n' bass.

Then there are the live performances, which can differ significantly from the exquisitely crafted studio songs. A U.S. tour last year -- especially some much-lauded shows at South by Southwest -- provided the substantial buzz that "After Robots" is extending now.

"Playing live, you allow the experience to take over and you improvise," explained bassist Molefi Makananise. Added vocalist Lindani Buthelezi, "Live and the studio are two different worlds and we want to learn from both. We don't just want to play the album."

"Either way, it's all Blk Jks," said Ramoba, noting that, because the band has been together since 2004, "we probably have 50 songs people haven't heard. We play some of those live, and we jam, keep it alive. We respect our audience."

Back in the days when "world music" was in one bin, South Africa was ruled by apartheid until Nelson Mandela was freed. Those remain the dominant images of South Africa for many Americans. When the members of Blk Jks are asked about the history they experienced as children and the ways in which politics informs their music, their answers are consonant with the forward thrust of the songs.

"If we have a political message, it is that music, like the cyberworld, the Internet, is making communication easier between us and the world is getting smaller," said Buthelezi.

"Put it this way," interjected rhythm guitarist Mpumi Mcata. "We can go on talking about change, or we can be the change already."