The Land of the Eternal Constellation, is a location and is the origins and home of the Solar Ponies before some of them moved to other locations.
The Land of Eternal Constellation is located at the very top left edge of the map. The area around the land was protected with an invisible magic field that would cause those who walked through it to experience a huge sense a fear, causing them to run. This magic resulted in the land's history remaining hidden from all, even to Princess Celestia and Princess Luna. This place was unknown to all, until recently. when the magic field faded, allowing others to pass through. Solar Ponies have lived in that area for thousands of years. They would spend their time studying the stars, sun and moon. When the era of Discord's reign came along, however, the Solar Ponies became frightened, and set up the magic field to try to prevent Discord from reaching their location. It worked, but the magic field backfired, and it couldn't be removed. Only recently the field broke, and they were discovered.