An underground city on the planet Alashan was the home of the ancient Alashan civilization. The city was buried five kilometers under the ground of Alashan. It was entirely powered by the city control center which maintained the lights and technological consoles throughout the massive city. In addition to supplying general power, the complex was also designed to create a Guardian for the city, to protect the Alashans from intruders.
At some undetermined time before the formation of the Republic, the Alashans disappeared from the giant city, leaving it as the only record of their existence. Around 0 ABY, Rebel archaeologists arrived on Alashan, and following sonic scans of the terrain, they discovered the gigantic city. However, when they eventually broke into the perfectly preserved construct, they found the Guardian waiting for them. The giant beast destroyed the intruders and left no one alive. Eventually, Rebel heroes Luke Skywalker, Leia Organa, and Mici Shabandar arrived to investigate the disturbance and entered the ancient city.
Along with Imperials Wil'm Grau and Anarine, the Rebels eventually succeeded in destroying the Guardian and the control center. Although the city powered down after the initial attack on the complex, as soon as the Rebels had left the world, the city inexplicably powered back up, apparently having succeeded in repairing itself.