An unidentified culture was the ancient civilization native to the planet Alashan. The culture had reached technological sophistication at a time well before the formation of the Galactic Republic. Among their accomplishments was the creation of a power source that was able to power the entirety of their massive underground city.
The power was also the source behind the Guardian of Forever, a powerful energy being designed to protect the city. Among other powers, the creature was able to fire a superlaser using the power of the city's control center which could destroy a target a hundred thousand kilometers from the planet's surface.
By the time of the Galactic Civil War, they had completely disappeared. Leaving the gigantic city of Alashan as the only monument to their existence, they sealed the city from the outside.