It may take a Ph.D. to fully grasp the politics, history and geography behind the varied cultural traditions at work in the Balkans and Eastern Europe, but a set of ears is all you really need to enjoy the music. Immigration has always fed the underground American obsession with Balkan and Eastern European music, but its fan base grew during the Cold War, when peaceniks around the country embraced the music of America's putative enemies as a way to break through the stultifying rhetoric on both sides. It was a home-grown affair that rarely registered beyond the cultural centers that hosted Balkan dance lessons and the occasional visiting musician. As the Cold War waned, it looked as if Balkan and Eastern European folk music would remain a niche genre for recent immigrants and the people who loved them. But in recent years, younger musicians have seized on it, inspired by the different time signatures, the minor-key melodies and, no doubt, its relative obscurity. The revival of interest in Balkan and Eastern European music has spelled a renaissance for a genre once dismissed as too "ethnic" for the mainstream, and breathed life into music scenes that were hungry for fresh ideas.