This is an incomplete list of heavy metal festivals.
 Heavy metal (or simply metal) is a genre of rock music that developed in the late 1960s and early 1970s, largely in the United States and the United Kingdom.
 With roots in blues rock and psychedelic rock, the first heavy metal bands such as Led Zeppelin, Black Sabbath and Deep Purple attracted large audiences, and during the late 1960s and mid-1970s these band and others in their genre were featured at a number of historic rock festivals. Judas Priest helped spur the genre's evolution by discarding much of its blues influence.
Carlos Santana    (born July 20, 1947) is a Mexican and American musician who first became famous in the late 1960s and early 1970s with his band, Santana, which pioneered a fusion of rock and Latin American music.
 The band's sound featured his melodic, blues-based guitar lines set against Latin and African rhythms featuring percussion instruments such as timbales and congas not generally heard in rock music.
 Santana continued to work in these forms over the following decades.
 He experienced a resurgence of popularity and critical acclaim in the late 1990s.
 In 2003 "Rolling Stone" magazine listed Santana at number 20 on their list of the 100 Greatest Guitarists of All Time.
 He has won 10 Grammy Awards and three Latin Grammy Awards.
Progressive rock is a radio station programming format that emerged in the late 1960s, in which disc jockeys are given wide latitude in what they may play, similar to the freeform format but with the proviso that some kind of rock music is almost always played.
 It enjoyed the height of its popularity in the late 1960s and 1970s.
 The name for the format began being used circa 1968, when serious disc jockeys were playing "progressive 'music for the head'" and discussing social issues in between records.
 During the late 1960s, as Long playing records began to supplant the single in popularity with rock audiences, progressive rock stations placed more emphasis on album tracks than their AM counterparts.
<ref name="Prog. radio/albums"> </ref> Throughout the 1970s as FM stations moved to more structured formats, progressive radio evolved into Album-oriented rock (AOR).
Imagine the Sound is a 1981 Canadian documentary film about free jazz, directed by Ron Mann.
 It features interviews with and musical and dramatic performances by pianist Cecil Taylor, saxophonist Archie Shepp, trumpeter Bill Dixon and pianist Paul Bley.
 The film has been digitally restored and was screened at the 2007 SXSW festival in Austin, Texas.
Psychedelic soul, sometimes called black rock, is a music genre that emerged in the late 1960s which saw soul musicians embrace elements of psychedelic rock, including its production techniques, instrumentation, effects units (wah-wah, phaser, etc.) and drug influences.
 It came to prominence in the late 1960s and continued into the 1970s, playing a major role in the development of funk and disco.
 Pioneering acts included Sly and the Family Stone, Jimi Hendrix, and the Temptations.
 Mainstream acts that developed a psychedelic sound included the Supremes and Stevie Wonder.
 Acts that achieved notability with the sound included the Chambers Brothers, the 5th Dimension, Edwin Starr, and George Clinton's Funkadelic and Parliament ensembles.
Progressive country is a subgenre of country music developed in the early 1970s.
 In the late 1960s and early 1970s, mainstream country music was dominated by the slick Nashville sound and the rock-influenced Bakersfield sound of artists like Merle Haggard.
 A new generation of country artists emerged, influenced by contemporary rock music, singer-songwriters such as Bob Dylan, and the liberal politics of the 1960s counterculture.
The Little Boy Blues were an American garage rock band from Chicago, Illinois active in the mid to late 1960s, who are considered early pioneers in protopunk.
 They are best known for songs such as "The Great Train Robbery" and their version of Van Morrison's "I Can Only Give You Everything," both of which are considered garage classics.
 Throughout their tenure, they underwent several personnel changes and in the late 1960s began to evolve their sound into a more sophisticated direction, before disbanding in 1969
Archie Shepp (born May 24, 1937) is an American jazz saxophonist.
 Shepp is best known for his passionately Afrocentric music of the late 1960s, which focused on highlighting the injustices faced by African Americans, as well as for his work with the New York Contemporary Five, Horace Parlan, and his collaborations with his "New Thing" contemporaries, most notably Cecil Taylor and John Coltrane.
Lost Nite Records was an American reissue independent record label, that was founded by Al Trommers, Jerry Greene, Jared Weinstein and Johnny Esposito in 1959 when they acquired the masters of "There's A Moon Out Tonight" by the Capris from Planet Records and rereleased it on Lost Nite in 1960.
 After this, Jerry and Jared relocated to Philadelphia from New York City.
 At this time, disc jockey Jerry Blavat was a partner in label until the late 1960s, at which time he sold back his interest in the company to Greene and Weinstein.
 Lost Nite, and its sister label Crimson Records, were known for releasing rare and hard-to-find doo-wop and R&B records.
 Lost Nite was one of the few labels responsible for keeping the doo-wop genre alive during the late 1960s and 1970s.
 The most popular single released by the label was "There's A Moon Out Tonight" by The Capris.
 After the demise of Lost Nite, founder Jerry Greene established Collectables Records in 1980.
Jazz fusion (also known as fusion) is a musical genre that developed in the late 1960s when musicians combined aspects of jazz harmony and improvisation with styles such as funk, rock, rhythm and blues, and Latin jazz.
 During this time many jazz musicians began experimenting with electric instruments and amplified sound for the first time, as well as electronic effects and synthesizers.
 Many of the developments during the late 1960s and early 1970s have since become established elements of jazz fusion musical practice.

Question: Who is the featured in the documentary,  Imagine the Sound, and is known for his passionately Afrocentric music of the late 1960s?
Answer: Archie Shepp