Short answers, pulled from the story.
The Black Mages were formed in 2002 by Nobuo Uematsu, Kenichiro Fukui, and Tsuyoshi Sekito, all video game composers at Square and Square Enix. The band expanded to six members in 2003 with the addition of Keiji Kawamori, Michio Okamiya, and Arata Hanyuda.
The Black Mages disbanded on the 7th of August 2010. In an April 2011 interview, Uematsu explained the main reason was that the band had been formed as a Square Enix entity, which prevented them from performing arrangements of music he composed after leaving Square Enix.
The Black Mages released three studio albums: The Black Mages in 2003, The Black Mages II: The Skies Above in 2004, and The Black Mages III: Darkness and Starlight in 2008. All three arranged Final Fantasy music in a hard rock and progressive metal style.
The Black Mages' self-titled debut album reached No. 43 on the Japan Oricon charts. It was released on the 19th of February 2003 by DigiCube and later re-released on the 10th of May 2004 by Square Enix.
The Black Mages performed in North America for the first time on the 16th of May 2005 at the More Friends: Music from Final Fantasy event at the Gibson Amphitheatre in Los Angeles, California. That was their only known performance outside Japan.
After The Black Mages disbanded, Uematsu formed the Earthbound Papas. He built the new band to exclude current Square Enix employees, which freed it from the trademark and licensing restrictions that had limited The Black Mages to Final Fantasy music.