After seeing what happened when she accidently changed her friends destinies, Twilight is curious about about the 'what if'. Like, for example, what if Luna had ponies a thousand years ago who noticed her.
The nation of Equestria holds little space in the history books of both the Solar Empire and the Lunar Republic. It was a forgotten nation. A nation that would split and crumble, and two more would rise from its ashes.