Question:
Vampire Weekend are an American rock band from New York City, formed in 2006. They are currently signed to Columbia Records. The band consists of lead vocalist and guitarist Ezra Koenig, drummer and percussionist Chris Tomson and bassist and backing vocalist Chris Baio. The band's first album Vampire Weekend (2008) - which included the singles "Mansard Roof", "A-Punk", "Oxford Comma", "Cape Cod Kwassa Kwassa" and "The Kids Don't Stand a Chance" - was acclaimed by critics for its world music influences.
After remaining quiet following the conclusion of their Modern Vampires tour, on January 26, 2016, Rostam Batmanglij announced his departure from the band on Twitter. He noted that he and Koenig would continue to collaborate. Later the same day, Koenig announced that Vampire Weekend was in the studio working on their upcoming fourth album, with Batmanglij contributing to the record. The album's working title was revealed to be Mitsubishi Macchiato. In April 2016, the band briefly performed at a rally for presidential candidate Bernie Sanders in Washington Park Square. Koenig has been a well-known supporter of Sanders, after discussions on his Beats 1 radio show, Time Crisis. The band performed live with Dave Longstreth of the Dirty Projectors, which marked their first performance as a trio. In late 2016, Koenig was reportedly in talks to sign the band with Columbia Records, as he reportedly "hit it off" with executive, Rob Stringer. Initially, this news was regarded a rumour, until the band's website revamp in 2018, in which a Sony Music copyright appeared on the site. In March 2017, Koenig revealed in an elaborate Instragram update that during 2016 he had spent countless hours researching and writing music in libraries with grad students. Additionally, he revealed that the album would feature a more 'spring-time' vibe and one of the songs would be entitled Flower Moon. Koenig revealed that LP4 would be partially inspired by the songwriting of country singer, Kacey Musgraves, after he attended one of her shows in September 2016. In an interview with Stereogum, he stated, "I'm the type of person who has spent hours poring over the avant-garde poetic lyrics of certain songwriters, and there was something that felt so good [about how] from the first verse, you knew who was singing, who they were singing to, what kind of situation they were in. After the show I realized there's not a ton of Vampire Weekend songs where you could listen to the first verse and immediately answer the question of who's singing and who are they singing to." Furthermore, in a September 2017 interview with Zane Lowe, Ezra briefly spoke about LP4 and stated that it was "about 80% done." He mentioned that the album would feature lead producer, Ariel Rechtshaid, with additional "guest appearances", one of which being Batmanglij. Lowe pushed Koenig for a release date, sighting Q1 2018 as a likely candidate. The band's first show since their hiatus was confirmed on January 31, 2018, when it was announced that the band would be headlining the UK music festival End of the Road. The festival will run from August 31 to September 3 and mark Vampire Weekend's first return to the stage in 4 years. Additionally, it was announced that they would headline the 2018 Fuji Rock Festival, scheduled for July 27 to 29. The band will also be performing at Lollapalooza 2018, which runs from August 2-5, 2018.
Answer this question using a quote from the text above:

Why did he leave

Answer:
He noted that he and Koenig would continue to collaborate.

Question:
Celtic Frost () were a Swiss heavy metal band from Zurich. They are known for their strong influence on the development of extreme metal. Formed in 1982 as Hellhammer, the band became Celtic Frost in 1984 and was active until 1993. It re-formed in 2001 and disbanded following frontman Tom Gabriel Fischer's departure in 2008.
Celtic Frost's frontman, guitarist and singer Tom Gabriel Fischer, adopted the alias Tom Warrior. With Steve Warrior on bass, he formed one of the earliest extreme metal bands, Hellhammer, in 1981. Steve Warrior was later replaced by Martin Eric Ain - also a pseudonym. The band attracted a small international fan-base, got signed to Noise Records in Germany and recorded their debut EP Apocalyptic Raids in March 1984, now a rare find on eBay or second-hand record stores around the world. Metal publications were also skeptical of Hellhammer's musical endeavor. Metal Forces loathed the group; that started a long-lasting feud between that zine and Warrior, which kept Celtic Frost from playing in England for a couple of years. Rock Power was not fond of Hellhammer either - they considered it "the most terrible, abhorrent, and atrocious thing 'musicians' were ever allowed to record". In fact, they were "receiving miserable reviews everywhere", Warrior concluded. Regarding the controversial status of his former band, Thomas said: Way back in 1984 and 85, when Martin Eric Ain and I recorded Celtic Frost's first two albums Morbid Tales and To Mega Therion, Hellhammer lasted on us almost like a curse. Even though Hellhammer was the very reason we had thought over our goals and conceived the Frost, HH's left-overs kept being mighty rocks in our way. Many voices saw Frost as the same band with just a name-change. The lack of musical quality in HH made it almost impossible for us to get an unbiased reaction for Frost. To make a long story short, it almost killed all our work and dreams. By May 1984, Hellhammer had disbanded. Fischer and Ain, along with session drummer Stephen Priestly, regrouped as Celtic Frost. Their 1984 debut mini-LP, Morbid Tales was a hit in the underground metal scene, and the band set out on its first tour, through Germany and Austria. This was followed with an EP Emperor's Return. Both early releases are now available on the one CD.
Answer this question using a quote from the text above:

Who else was part of this band?

Answer:
Steve Warrior