Jean Claude Van Damme with his Ass All Tight!

Buraka Som Sistema has played sold-out shows in London and New York. MIA guest starred on "The Sound of Kuduro" -- the single that earned them a spot on Pitchfork Media's Best Tracks of 2008. Even Justin Timberlake has raved about them on his blog. So why isn't Buraka Som Sistema's "The Sound of Kuduro" having the same radio success as MIA's "Paper Planes"?

It could be because Buraka Som Sistema raps largely in Portuguese, but it's more likely due to the nature of kuduro itself. The amped-up music must necessarily go hand-in-clammy-hand with its sweat-inducing dance. The only way to really experience kuduro and Buraka Som Sistema is to get your t-shirt soaked through while you're crushed against hundreds of fellow dancers in a tiny, overheated club. Kuduro mixes collapse-to-the-floor theatrics with intense pop and lock breaks, setting the fervent dance to a soundtrack of accelerated, high-energy jungle music.

The blogosphere has been abuzz with all things kuduro since last summer, but if you think its fifteen seconds of fame have passed, you haven't heard Buraka Som Sistema's new mix tape (available here, for free).

Kuduro began in the shantytowns of Angola during the 27-year civil war, but the Angolan ass-shaking phenomenon quickly spread to Portugal, Brazil and the UK, with each region adding its own distinctive stamp. The kuduro of Angola, like the baile funk of Rio and kwaito of South Africa, was a product of its environment -- aggressive beats and in-your-face rhymes that matched the country's civil unrest. But it wasn't long before the youth of neighbouring nations were seizing upon kuduro and making the movement their own. The word "kuduro" translates to "hard butt" in Portuguese, so of course Angola's unique musical export is now a mainstay in the booty-shaking, Portuguese-speaking city of Lisbon.

And right now, Buraka Som Sistema is the most recognizable name in kuduro. The Lisbon group of MCs and DJs gained notoriety with their 2008 album Black Diamond, and they released the follow up mix tape in July. Among its delights is a remix of "Diamonds on the Soles of her Shoes" by Paul Simon and "Dance Dance Dance" by Swedish indie darling, Lykke Li.

Western exposure to Buraka Som Sistema and the kuduro movement is fueled by hundreds of YouTube videos that could easily shift kuduro from obscurity to ubiquity at any moment, but purists needn't worry about the West polluting the genre -- it's been an influence from the start. In an interview with Reuters, Tony Amado, an Angolan musician who helped devise kuduro said, "I always liked to imitate Michael Jackson, but when I saw [Jean Claude] Van Damme dance in that movie with his ass all tight I immediately starting singing: dance, dance Van Damme, dance, dance Van Damme!" Van Damme's clenched cheeks add a whole other layer to the "hard butt" definition, but when you get down to the nitty-gritty -- and with Buraka Som Sistema you will -- the Muscles from Brussels got it right: kuduro is all about the booty shake.