 Scholar <unk> von Helden acknowledges that " There are difficulties in defining [ Viking metal ] , because the definition — apart from certain elements like anthem @-@ like choruses — is not based entirely on musical features and overlaps with other metal genres . The music derives from the also Scandinavian @-@ coined genres of black and death metal . " Some bands , such as Unleashed and Amon Amarth , play death metal , but incorporate Viking themes and thus are labeled under the genre . Scholar Heather O 'Donoghue also notes how Viking metal is defined more by its thematic material than musical qualities . She writes that " Viking metal draws on Norse themes not in a strictly musical sense — the work of groups such as Bathory is not by any means a mock @-@ up of medieval music . Rather , it is in the band names , album titles , artwork of album covers and , especially , in the song lyrics that Viking themes are so evident . " Irina @-@ Maria Manea in " Primal Roots : Ancestry and Race in Extreme Music Discourses " considers Viking metal , and the closely related style pagan metal , more of a term or " etiquette " than a musical style . She elaborates that " Viking and Pagan Metal are more likely lyrical subgenres distinguished primarily by their content and less by sound characteristics , which is why categorizations may come out as controversial . " Ashby and Schofield also consider Viking metal more of a cross @-@ genre term than a descriptor of a certain sound . They write that " The term ' Viking metal ' is one of many that falls within a complex web of genres and subgenres , the precise form of which is constantly shifting , as trends and fads emerge and fade . " They note further on that from its origins in black metal , Viking metal " has diversified ( at least in aural terms ) , and now covers a range of styles that run the gamut between black metal and what one might justifiably term classic rock . " 
