After founding HELO Media in support of that mission, Gerstle met Travis Beard, an Australian musician and videographer who has been living in Kabul for several years and who, along with his rock band, White City, is the driving force behind the music festival.

Sound Central brings together artists from across Central and South Asia, including four groups from Afghanistan's nascent post-Taliban rock scene. It was going to be the first Afghan rock festival since 1975, when the 'Afghan Elvis,' Ahmad Zahir held a show during the heyday of the capital's brief, ill-fated cultural liberalization under King Zahir Shah. Times have changed: a couple of days before the Brooklyn show, a team of suicide bombers attacked the U.S. embassy, resulting in a 20-hour siege that paralyzed downtown Kabul.

This level of violence obviously poses logistical challenges for holding a music festival. As Gerstle explained, they would be operating a "stealth festival," with concerts and venues to be announced shortly beforehand by text messages or on Facebook and Twitter. Their low profile is also a way of avoiding any cultural controversies that might in triggered in as conservative an atmosphere as Afghanistan's.

The connection between war and rock seems to be an obvious one in the popular imagination. When you watch a war movie, the soundtrack to the action scenes is usually rock music. In actual warfare, troops sometimes like to imagine themselves as rock and rollers, and on embeds with the U.S.-led force in Afghanistan I've heard "let's rock and roll" more than once as troops armed their weapons before heading out on patrol. And, to complete the life-imitates-art loop, the montages of combat footage that soldiers lovingly compile are almost invariably set to heavy metal soundtracks.

Maybe that connection is partly because rock and roll is about channeling some of the same primal enthusiasms in young people -- showy risk, physical exertion, and sweaty camaraderie -- expressed in warfare. Ironically, the politics of rock --insofar as it represents, or once represented, a counter-cultural movement -- tend towards the anti-war.

One senses that ambiguity in Sound Central's self image. Their promo materials play up the war connection --"You're used to the sound of bombs. Now get used to the sound of metal," you hear the Afghan death metal group District Unknown growl at the start of their video. But, at the same time, it's clear that these artists see rock music as a way to escape from war, even of finding some kind of normalcy or apoliticism in an environment inevitably viewed, in the West, through the prism of the "conflict zone."

After an on-stage introduction to Sound Central by Gerstle (who would fly to Kabul shortly afterwards), artists like Acrassicauda, a heavy metal band from Iraq, and Shayan Amini, a rocker from Tehran, got on stage to talk about their experiences. Both have fled their countries under the threat of violence. As they told their stories to the assembled crowd -- who seemed to be mostly, like myself, relatively privileged, educated youths -- one could observe a real appreciation and amazement forming on many of our faces. It wasn't just that these kids were brave or had interesting stories; it's that they were channeling the true spirit of rock and roll.