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...