Heavy metal music
Critics disagree over who can be thought of as the first heavy metal band. Most credit either Led Zeppelin or Black Sabbath, with American commentators tending to favour Led Zeppelin and British commentators tending to favour Black Sabbath, though many give equal credit to both. A few commentators—mainly American—argue for other groups including Iron Butterfly, Steppenwolf or Blue Cheer. Deep Purple, the third band in what is sometimes considered the "unholy trinity" of heavy metal (Black Sabbath, Led Zeppelin, and Deep Purple), despite being slightly older than Black Sabbath and Led Zeppelin, fluctuated between many rock styles until late 1969 when they took a heavy metal direction.
List of Viking metal bands
Though artists such as Led Zeppelin, Yngwie Malmsteen, Heavy Load, and Manowar have previously dealt with Viking themes, Bathory from Sweden is generally credited with pioneering the style with its albums "Blood Fire Death" (1988) and "Hammerheart" (1990), which launched a renewed interest in the Viking Age among heavy metal musicians. Enslaved, from Norway, followed up on this burgeoning Viking trend with "Hordanes Land" (1993) and "Vikingligr Veldi" (1994). Burzum, Emperor, Einherjer, and Helheim, among others, helped further develop the genre in the early through mid-1990s. Through the work of artists such as the German project Falkenbach, Viking metal soon spread from the Nordic countries to other nations with Viking history or an even broader Germanic heritage, and has since influenced musicians across the globe. The death metal bands Unleashed and Amon Amarth, which emerged in the early 1990s, also adopted Viking themes, broadening the style from its primarily black metal origin.