Question: Ehnahre is a ensemble of a music subgenre that has developed since the early what?

<P0-S0> Extreme metal is a loosely defined umbrella term for a number of related heavy metal music subgenres that have developed since the early 1980s. <P0-S1>  It has been defined as a "cluster of metal subgenres characterized by sonic, verbal and visual transgression". <P0-S2>  The term usually refers to a more abrasive, harsher, underground, non-commercialized style or sound associated with the speed metal, thrash metal, death metal, black metal and doom metal genres. <P0-S3>  With the exception of doom metal, all of these genres are characterized by fast tempos, attesting to their roots in hardcore punk, which has also fused with extreme metal in the forms of crossover thrash, crust punk, grindcore, sludge metal and metalcore. <P0-S4>  Though many extreme sub-styles are not very well known to mainstream music fans, extreme metal has influenced an array of musical performers inside and outside heavy metal. <SEP> <P1-S0> Go-go is a popular music subgenre associated with funk that originated in the Washington, D.C., area during the mid-60s to late-70s. <P1-S1>  It remains primarily popular in the Washington metropolitan area as a uniquely regional music style. <P1-S2>  A great number of bands contributed to the early evolution of the genre, but the Young Senators, Black Heat, and singer-guitarist Chuck Brown & the Soul Searchers are credited with having developed most of the hallmarks of the style. <SEP> <P2-S0> Flamenco rock or Andalusian rock is a rock music subgenre that emerged from (but is not limited to) the Spanish region of Andalusia throughout the late 1960s and early 1970s. <P2-S1>  There were some precedents like a couple of albums ("Rock encounter (with Joe Beck)" and "The Soul of Flamenco and the Essence of Rock") by Sabicas, a couple of singles ("El garrotín / Tangos de Ketama" and "Ni recuerdo ni Olvido") by Smash, Gong, Galaxia, Flamenco or even the American band Carmen. <P2-S2>  However, Triana was recognized as a pioneer of the genre since their music focuses on a complete fusion of the progressive rock and flamenco. <P2-S3>  Many bands that mix progressive and symphonic rock with flamenco followed them such as Imán Califato independiente, Cai, Guadalquivir, Alameda or Mezquita; that's why the term "Andalusian rock" may be understood simply as flamenco prog. <P2-S4>  Medina Azahara turned from progressive to a hard rock outfit in the 1980s and they remain as one of the most popular flamenco rock bands in its home nation. <P2-S5>  Also other flamenco-influenced styles of rock emerged like the flamenco-folk band Veneno, flamenco-jazz-blues band Pata Negra among other bands that melted flamenco with African, reggae or Latin rhythms. <SEP> <P3-S0> Ehnahre is an experimental Extreme metal ensemble and contemporary composition collective based in Boston, Massachusetts. <P3-S1>  Their music incorporates elements of Contemporary classical music, Aleatoric music, Doom metal, and Death metal, and utilizes extended techniques, aleatoric rhythms, aspects of Serialism, and elements from free improvisation, contemporary chamber music, and extreme metal styles.