The Crystal Empire (1)

Northern Equestria's Crystal Empire has once again made an appearance after being afflicted with a curse that made it vanish for 1,000 years, and Princess Celestia commissions Twilight Sparkle to keep the empire from disappearing again.
My Little Pony: Friendship is Magic - Season 3, Song #1: "The Failure Song"
My Little Pony: Friendship is Magic - Season 3, Song #2: "The Ballad of The Crystal Ponies."