The Ancient City of Xan existed in the Old World Hemisphere, by the northern shore of the continent of Urrika, on Superman's home planet of Krypton. At the time of Krypton's destruction however, the once mighty ancient city was already in ruins (S No. 239, Jun-Jul 1971: "Map of Krypton").
Little is known of it's history or people, however it has been recorded that at some point in its history, it was at war with the city of Erkol, and was responsible for Erkol being destroyed. (S No. 248/2, Feb 1972: "All In The Mind").
By approximately 500 years before the destruction of Krypton, Xan was completely deserted and served as a hideout for Nam-Ek. (S No. 282/2, Dec 1974: "The Loneliest Man In The Universe")