Long, long ago, there was a pony with a name forgotten today, who lived in Equestria. Equestria was beautiful, and there was bonds between all. Everything was perfect. Almost. The three clans fought often, which enraged this unicorn. She understood that earth ponies had inferior magic abilities as opposed to her kin. However, she saw no reason to argue about it. As time went on, the little filly grew up, seeing multiple villains suppressed by the two princesses. This angered her even further, as she thought it was stupid that the fate the land was in the hooves of only two ponies. They were alicorns, that was true, but that didn't make it any better. She dreamed of a land that was protected by all the ponies as a whole. It never happened. It was pleasing, however, that racial feuds had died down. That was something to be thankful for. But she still wished for a better life.
One day, she and a large group of ponies sharing her opinions worked together to dig a great, cavernous area far below the ground of Equestria. They created an illusion that made the ceiling seem to be the sky, but placed a magical barrier a bit below the cieling, with plans to claim it was for safety, so that no pony was burnt by the sun. They created rolling hills, and jagged mountains, deep, cold lakes. It was just as beautiful, if not more so, as Equestria. There was even a region like Cloudsdale, where only those of the pegasus breed resided. The unicorn became the ruler, and the place slowly filled in as Equestria lost some of its citizens.
When there was finally enough for a kingdom, she wiped their memories, and led them to believe they'd lived there all their lives. She ruled over them kindly, and they faced all dangers as a whole. On her last day of life, she was happy. The world she'd always dreamed of had become a reality. However, before she let herself go, she assigned a pegasus a great task. She must rule in the unicorn's place as ruler of Falinn, which was the name of this land. So, after the pegasus agreed, she left. She died that day, as she'd known she would, because her magic power was depleted in the making of her paradise. Ponies of this land never knew they were underneath another kingdom. They merely believed they were the only beings around, as well as all the animals that roamed the forests, lakes, plains, and mountains.