Today’s “world music” isn’t Peruvian pan flutes or African talking drums. It’s loud guitars, growling vocals and ultrafast “blast” beats. Heavy metal has become the unlikely soundtrack of globalization.

Indonesia is a metal hotbed: Its president, Joko Widodo, wears Metallica and Napalm Death T-shirts. Metal scenes flourish in Latin America, Eastern Europe, Russia and Scandinavia. China got an early seeding of metal 25 years ago when U.S. record companies dumped unsold CDs there. In a male-dominated genre, Russian band Arkona is fronted by singer Maria Arkhipova. Language barriers are less significant in the metal world, which is all about the sound, an often dissonant drone not grounded in any one musical tradition.

The explosion of local bands around the world tends to track rising living standards and Internet use. Making loud music is expensive: You need electric guitars, amplifiers, speakers, music venues and more leisure time.

“When economic development happens, metal scenes appear. They’re like mushrooms after the rain,” says Roy Doron, an African history professor at Winston-Salem State University.

Record labels are paying more attention now. At Nuclear Blast Records, one of metal’s biggest independent labels, global retail sales rose last year to 2.53 million albums, up from 2.25 million in 2014 and 1.84 million in 2013. In the late 1990s and 2000s, Nuclear Blast made a bet on bands with a potential to sell well globally, such as Norway’s Dimmu Borgir and California veterans Exodus, says Gerardo Martinez, U.S. manager for Nuclear Blast. Since he joined the company in 2003, payroll has doubled to 200 employees in five offices including Germany and Brazil.