Metal isn't over the hill, even if it is reaching around 40 years in the world of music. In fact, metal, with its fast, heavy, rhythmic guitars, bass ablaze, drums pulsating beat by beat and fist-in-your-face vocal growls is spreading like a virus. Just look at the loads of subgenres: classic, thrash, power, groove, glam, gothic, symphonic, death, black, melodic, modern and there is even more out there with legions of rabid fans to support them.

Hailing from Sweden, some might term the band Amon Amarth "Viking" metal due to their repetitive lyrical references to Norse mythology. The band originally went by the name of Scum, until different members mixed with the band, forming what is now Amon Amarth, in 1992. The metal mongers then signed onto Metal Blade records in 1998 and have been releasing albums since then, with their most recent being With Oden On Our Side.

The band name itself comes from a place in J.R.R. Tolkien's famous and fictional Middle-earth. "It's not really as far fetched as you might think since Tolkien took inspiration from Scandinavian mythology himself," says Amon Amarth vocalist, Johan Hegg.

Despite the bands undying passion for Norse mythology and the Viking age, they feel their music shouldn't necessarily be described as "Viking" metal. "We play metal is the easiest way to say it," says Hegg. "Because of the vocal style and everything of course I guess you would have to describe it as death metal. Swedish death metal."

While winding up the conversation with Hegg, he warns his future audiences to, "warm up you necks properly, because we're going to kick your ass and want to see some head banging."

Touring on a variety of metal tours across the world, this will be the first time Amon Amarth headlines their own U.S. tour, performing with other acts such as Himsa, A Life Once Lost and Sonic Syndicate.

Sonic Syndicate is a bit different from Amon Amarth in metal genres, but will be crossing the Atlantic from Sweden just the same. "It's more like melodic metal or modern metal. I don't think it's that much death metal stuff we're doing. I'd rather call it melodic metal or modern metal, because that is really what it is," says Sonic Syndicate vocalist Richard Sjunnesson by phone while getting ready for a show in Gothenburg, Sweden.

Whatever it is, the sound got Sonic Syndicate signed onto Nuclear Blast records after they won Nuclear Blast's Europe wide band contest. They recently released their second studio album, Only Inhuman.

The album features tracks with melodic vocals by Roland Johansson and growling vocals by Sjunnesson with a metal-meets-hardcore vibe. The band even does a little less sweet, a little more bitter cover of the song "All About Us," previously a single by the Russian band T.A.T.U. and written by The Veronicas, Billy Steinberg and Josh Alexander.

"Definitely, when we released the album and got picked up by Nuclear Blast and stuff like that, everything had happened. Even though we released stuff before that, we were still pretty anonymous," says Sjunnesson. "We were the first band to ever sign to Pivotal [Rockordings] and they didn't really have the budget to push and stuff like that. Now things are starting to move."

This tour will be Sonic Syndicate's first time in the United States. The Polish metal band, Decapitated, was also supposed to be on the tour, but had to drop out due to a recent bus accident in Russia that left their drummer, Witold "Vitek" Kieltyka, dead and other members in recovery.

So what is the deal with all these foreign metal bands? Why do Amon Amarth and Sonic Syndicate believe so many metal bands are popping out of their own country?

Hegg believes it is primarily due to public music schools and youth clubs run by various communities that allow kids to learn to play and borrow instruments.

"Something in the water, no, I don't know," Sjunnesson says. "The government is pushing the bands in a lot of ways and it's easy to get, like, rehearsal rooms and the opportunity to get in a band and stuff like that. So, I guess with all these bands some just happen to reach the surface."

Amon Amarth will perform with Sonic Syndicate and A Life Once Lost at Tremont Music Hall on Thursday, Nov. 29. Doors open at 7 p.m. Tickets are $16 in advance, $19 day of the show.