A Jedi Library was constructed by the ancient Jedi Order upon the moon known as Yavin 4. This library formed a section of the Lost City of the Jedi, a subterranean city and terraforming facility established by the Jedi Order. Its purpose was to revitalize the moon's environment after the devastation caused by the Great Sith War. The majority of the library's information was stored inside a master computer, which held data inputted by the Jedi themselves. In addition to the computer, the library also housed aged books and handwritten texts on its shelves. Furthermore, preserved within display cases were ancient Jedi relics and artifacts.
This revered Jedi Library was impeccably kept by numerous generations of droids, which occasionally went to the surface to collect data and refresh the databanks. The Library's immaculate floor was defiled for the first time in thousands of years in 5 ABY when a team of Imperial operatives, commanded by the self-proclaimed Supreme Prophet of the Dark Side, Kadann, invaded it. Rebel Alliance forces cornered the false prophet and his soldiers inside the Library, and a stormtroopers inadvertently ruined the grand computer.