Question: Pigs of the Roman Empire featured the guitarist from an American rock band from Los Angeles, California, formed in what year?

Context paragraphs:
Bad Religion discography: The discography of Bad Religion, an American punk rock band, consists of 16 studio albums, two live albums, four compilation albums, one box set, two extended plays (EPs), 29 singles, five video albums and 23 music videos. Formed in Los Angeles, California in 1980, the band originally featured vocalist Greg Graffin, guitarist Brett Gurewitz, bassist Jay Bentley and drummer Jay Ziskrout, who released their self-titled debut EP in February 1981 on Gurewitz's label Epitaph Records.  Pete Finestone replaced Ziskrout before the release of the band's full-length debut album "How Could Hell Be Any Worse? " in 1982.  The following year's "Into the Unknown" featured bassist Paul Dedona and drummer Davy Goldman, before Bentley and Finestone returned to the band and Greg Hetson joined as second guitarist.

Young Dubliners: The Young Dubliners (sometimes shortened to the Young Dubs) is an American rock band formed in Los Angeles, California in 1988.  Their style of music has come to be called Celtic Rock for the fusion of Irish traditional instruments and music with modern rock.  They have released ten albums, starting with "Rocky Road" in 1993 and most recently "9" in 2013.  They have toured the United States and Europe since 1994, supporting Jethro Tull, John Hiatt, Chris Isaak, Jonny Lang, Great Big Sea and Collective Soul.  AllMusic.com states, "Their live shows (have) a jam-like appeal, similar to the vibes of Phish and the Dave Matthews Band."  Members include lead vocalist and guitarist Keith Roberts, bassist Brendan Holmes, violinist Chas Waltz, guitarist Bob Boulding and drummer David Ingraham.  Their repertoire consists mostly of original rock compositions and Irish folk songs with a rock twist.  Their influences include Thin Lizzy, The Pogues, The Waterboys and U2.

Austin Young: Austin Young (born April 12, 1966) is an American photographer, film maker and new media artist currently based in Los Angeles.  His work has created an encyclopedic documentation of sub and trans culture in New York, Los Angeles and San Francisco.  Young's photographs have been featured in major publications such as Interview magazine, OK, and Flaunt and have been shown in solo exhibitions and projects at LACMA (Los Angeles, CA), Machine Project (Los Angeles, CA), Hammer Museum (Los Angeles, CA), Berkeley Art Museum (Berkeley, California); and as well as groups shows at Los Angeles Contemporary Exhibitions (Los Angeles, CA) and Stephen Cohen Gallery (Los Angeles, CA).  In addition to photography and film making, Young is co-founder of Fallen Fruit, an art collective who use fruit as a common denominator for public engagement and collaboration.

Pigs of the Roman Empire: Pigs of the Roman Empire is an album by the American alternative metal group Melvins and electronic musician Lustmord, which was released in 2004 through Ipecac Recordings.  Adam Jones, guitarist for Tool, also makes substantial contributions to the album.

Best Coast: Best Coast is an American rock duo formed in Los Angeles, California in 2009.  The band consists of songwriter, guitarist and vocalist Bethany Cosentino and guitarist and multi-instrumentalist Bobb Bruno.  Cosentino, a former child actress, began writing music as a teenager and was formerly a member of the experimentalist drone group Pocahaunted.  After a brief tenure at college in New York City, Cosentino returned to the West Coast and began recording lo-fi demos with Bruno, whom she met in the Los Angeles music scene.

Tool (band): Tool is an American rock band from Los Angeles, California.  Formed in 1990, the group's line-up includes drummer Danny Carey, guitarist Adam Jones, and vocalist Maynard James Keenan.  Justin Chancellor has been the band's bassist since 1995, replacing their original bassist Paul D'Amour.  Tool has won three Grammy Awards, performed worldwide tours, and produced albums topping the charts in several countries.

Los Angeles flood of 1938: The Los Angeles flood of 1938 was one of the largest floods in the history of Los Angeles, Orange, and Riverside Counties in southern California.  The flood was caused by two Pacific storms that swept across the Los Angeles Basin in February-March 1938 and generated almost one year's worth of precipitation in just a few days.  Between 113–115 people were killed by the flooding.  The Los Angeles, San Gabriel and Santa Ana Rivers burst their banks, inundating much of the coastal plain, the San Fernando and San Gabriel Valleys, and the Inland Empire.  Flood control structures spared parts of Los Angeles County from destruction, while Orange and Riverside Counties experienced more damage.

Acid Tiger (album): Acid Tiger is the self-titled debut studio album by the American rock band Acid Tiger.  The album was released on April 27, 2010 through Deathwish Inc. — a label that was co-founded by Jacob Bannon of Converge.  Acid Tiger is a supergroup composed of Ben Koller (Converge, All Pigs Must Die), Lukas Previn (Thursday, United Nations), Adam Wentworth (Bloodhorse, All Pigs Must Die) and J Rattlesnake.  The album has been compared to 90s math rock and the psychedelic rock band The Doors.

Kyle Gass Band: Kyle Gass Band (KGB) is an American rock band that was formed in Los Angeles, California in 2011.  Fronted by Tenacious D acoustic guitarist Kyle Gass and vocalist and guitarist Mike Bray.  The backing band consists of electric guitarist John Konesky (also of Tenacious D), bassist Jason Keene, and drummer Tim Spier.  The band has released two albums - "Kyle Gass Band" (2013) and "Thundering Herd" (2016).

Art of Chaos: Art of Chaos (also known commonly as AOC) is an alternative rock band from Los Angeles, California.  Over the past year, Art of Chaos has toured extensively in California, headlining shows up and down the coast.  The band also took part in last summer’s Projekt Revolution, after being personally asked by Linkin Park to join the tour for the entire southwest run.  Art of Chaos’ fan base is growing at a rapid rate, due to strong internet exposure and widespread talk over the Internet and television exposure on MTV2’s On Demand.  The band was also voted “Modern Rock Band of Year” and “Performer of the Year” at the 2007 Los Angeles Music Awards.  Art of Chaos is known for their energetic live shows and infectious, inspired rock.

Supporting paragraphs: Pigs of the Roman Empire Tool (band)
Answer: 1990