Everypony knows about Equestria. The nice country is a paradise. Friendship is life, and the Elements of Harmony protect that way of living. Ponies love and tolerate each other. They have no reason for mistrust, because no pony has anything to hide. All of Equestria is oblivious to life outside of their wonderland. . . all except three individuals.
Princess Celestia stood staring at a mirror deep within her palace. In it, she saw everything except herself. Her magical gaze swept across Equestria, watching all of her happy subjects. Nothing made her happier than knowing that her ponies were living well. However, that was not what she was looking for. She focused on the horizon, and her vision zoomed over the land. She passed many cities and other little towns, before she finally rested her eyes upon a set of mountains.
Celestia took a deep breath, and crossed the mountains. Her mentality instantly became weak and fragile as her mirror took her consciousness across the boundary of her magically protected domain. The land here was dark and barren. The remains of countless wars were scattered everywhere.
Luna, as well as Celestia, knew what all went on outside the Equestrian borders. So many wars had been fought by those attempting to get in. Everything outside believed that there was a powerful weapon inside that made it so impossible to get in. Everything knew to stay away from the magical barriers that protected Equestria, but none knew that it was the power of friendship that fueled all of it.
Something very few beings knew was that Princess Celestia was an incredibly special individual. It was assumed by her subjects that she was some sort of goddess, but none of them really guessed that it was love and friendship that gave her magic. With all of it that exists in Equestria, Celestia was able to keep up the magical protections. Luna, unlike her sister, had her own reservoir of magic. The amount of friendship in Equestria was the only reason Luna wasn't stronger than Celestia. Princess Luna used her powers to attack anything that came too close. Ever since they had defeated Discord and taken leadership, they had been successful.
However, Celestia was genuinely worried as she scanned the horizons. What she saw terrified her. Coming across the sky was a massive machination. It was hard to make out the fine details, but it was obviously airborne, with huge streams of fire pouring out from behind and under it. Never before had anything so big or intimidating ever been spotted.
As the machine came closer, Celestia knew it was time to tell Twilight Sparkle who she really was: the Astral Bridge. The link to a world of pure energy, and limitless power. The genetic key to breach that dimension had almost been completed with Luna, but Twilight was the first time since Star-Swirl the Bearded that a portal had ever been born. It was the secret to her "raw power" that Celestia had witnessed many times before.