Laconic / Year Zero

Trope: A specific event in the continuity is the start of an arbitrary calendar.

Literature: Humanity's music is rediscovered, and an alien race threatens to destroy the entire Earth after everyone learned the hard way that Digital Piracy Is Evil.

Music: Oppressive government controls the populace with drugs. There are some unfortunate side-effects.
http://tvtropes.org/pmwiki/pmwiki.php/Laconic/YearZero