The Expeditionary Library was a massive underground library located under the ice of the Chiss Ascendancy's capital planet of Csilla. The library contained the documents and works produced from the Chiss Expansionary Defense Force's exploration of the Unknown Regions, with most of it translated into Basic and in written form to prevent losing any data to ice storms. In 28 ABY, a Galactic Alliance–Imperial Remnant group led by Jedi Master Luke Skywalker visited the Chiss library in hopes of finding the location of the sentient world Zonama Sekot, and succeeded in pinpointing the position of the planet to the Klasse Ephemora system.