Question: Which rock band was formed first, Mazzy Star or A Perfect Circle?
Context: The discography of American alternative rock band Mazzy Star consists of four studio albums and ten singles.  The group formed in 1989 from Opal, with guitarist David Roback and bassist Kendra Smith.  When Smith left the band, she was replaced by vocalist Hope Sandoval.  Mazzy Star's first studio album was "She Hangs Brightly", released in 1990 on Capitol Records.  It was certified gold in the United States and spawned two singles, "Halah" and "Blue Flower." Keep Telling Myself It's Alright is the debut studio album by American rock band Ashes Divide, the solo-project by A Perfect Circle guitarist Billy Howerdel.  While efforts towards a Howerdel solo album were started even back in his time in A Perfect Circle during touring in support of their 2003 album "Thirteenth Step", commitments to A Perfect Circle and other projects, along with some difficult recording sessions, pushed the album's release out to April 8, 2008.  Its first single, "The Stone," entered radio circulation in January of that year. Mazzy Star is an American alternative rock band formed in Santa Monica, California, in 1989 from the group Opal, a collaboration of guitarist David Roback and bassist Kendra Smith.  Roback's friend Hope Sandoval became the group's vocalist when Smith left the band. Stoned & Dethroned is the fifth album by the Scottish alternative rock band The Jesus and Mary Chain.  After spending most of 1992 touring, including a slot on that year's Lollapalooza tour, the band went into the studio during January 1993 with the notion of recording an acoustic album.  For the first time since "Psychocandy", JAMC recorded with a full band with Steve Monti from Curve playing drums and touring bassist Ben Lurie.  The recording took longer than planned, lasting the better part of a year.  The album also features lead vocals from guests Shane MacGowan from The Pogues on "God Help Me" and Mazzy Star's Hope Sandoval, singing a duet with Jim Reid on "Sometimes Always", which was the album's first single. "I'm Less Here" is a stand-alone single released by alternative rock band Mazzy Star for Record Store Day 2014, and was the band's first release of new material since their previous album, "Seasons of Your Day".  The track had previously been performed live under the name "It Speaks of Distance," with its first known performance dating back to March 1994.  The A-side was backed by another previously unreleased song, titled "Things".  The day before the single's release, the band posted a music video for the track on their official Vevo account. A Perfect Circle Live: Featuring Stone and Echo is a live box set by American rock supergroup, A Perfect Circle.  It was released via the band's own label, A Perfect Circle Entertainment, on November 26, 2013, a week after the release of the band's greatest hits album, "Three Sixty". The discography of American alternative rock supergroup A Perfect Circle consists of three studio albums, two compilation albums, one extended play, one video album, nine singles, one promotional single and ten music videos.  A Perfect Circle is the brainchild of Billy Howerdel.  After hearing demos of Howerdel's music, Maynard James Keenan, the lead singer of Tool, offered his services as vocalist.  Howerdel agreed, and the band formed in 1999.  They were then joined by bassist/violinist Paz Lenchantin, guitarist Troy Van Leeuwen, formerly of Failure, and drummer Tim Alexander, formerly of Primus.  Soon after entering the studio to record their first album, Alexander was replaced by Josh Freese of The Vandals. " Mer de Noms" was released in May 2000, selling 188,000 copies its debut week.  The band embarked on a number of headlining tours all over the world to promote the album which was certified gold by the Recording Industry Association of America (RIAA) one month after its release, and platinum just four months later. Ashes Divide is the name used for the solo project of American rock musician Billy Howerdel, guitarist of the alternative rock band A Perfect Circle, where he is the primary songwriter, musician, producer, and vocalist.  The project's debut album, "Keep Telling Myself It's Alright", was released in 2008.  Howerdel formed a live band and toured in support of the album through the rest of the year, but the project fell to the wayside after A Perfect Circle reformed and toured in 2010 and 2011.  Howerdel would work on both projects for a while until late 2012, where he announced his primary focus is completing the second album, of which he hoped to enter the mixing phase in January or February 2013. A Perfect Circle is an American rock supergroup formed in 1999 by guitarist Billy Howerdel and Tool vocalist Maynard James Keenan.  A Perfect Circle has released three albums: their debut "Mer de Noms" in 2000, a follow up, "Thirteenth Step" in 2003, and an album of radically re-worked cover songs titled "Emotive" in 2004.  Shortly after "Emotive"' s release, the band went into hiatus while Keenan returned to Tool and starting up solo work in the form of the band Puscifer, and Howerdel releasing a solo album, "Keep Telling Myself It's Alright", under the moniker Ashes Divide.  Band activity was sporadic in the coming years; the band reformed in 2010, and played live shows on and off between 2010 and 2013, but fell into inactivity after the release of their greatest hits album, "Three Sixty", and a live album box set, "" in late 2013.  However, in 2017, the band returned to touring and announced plans to record and release a fourth studio album under a new record label, BMG Rights Management, between late 2017 and early 2018. She Hangs Brightly is the debut studio album by American dream pop band Mazzy Star.  It was released in 1990 on Rough Trade Records, following the demise of David Roback's previous band Opal.  The album was rereleased by Capitol later that same year.  The first track "Halah" was released as a single and reached #19 on the Billboard Alternative Songs chart.  It showcases the band's trademark effect with haunting guitar work and lyrics, and Hope Sandoval's detached vocals.  David Roback's Robby Krieger-inspired psychedelic blues slide guitar style can be heard on the song "Free".  "Ghost Highway" is another psychedelic rock track, with a fast rhythm.  This song dates from the band's days as Opal and was initially slated to be the title track of Opal's second album.  While not a commercial success, this album did establish Mazzy Star as a unique band with a unique sound.
Answer: Mazzy Star