The Xanno were a civilization. In 2255, when one of the members of James T. Kirk's team for a training simulation fled to Omaha, he was replaced by a Xanno named Braxim, the Academy's only Xanno cadet.

The Xanno migrated for over 450 years before founding New Xannon in the Alpha Quadrant. A legend of their species states that they originated in the Delta Quadrant, a fact born out by a classified Priority Three level study of Xanno history by Starfleet Intelligence prior to their admission to the United Federation of Planets in 2229. Leonard McCoy called the evidence in the study "pretty definitive." (TOS novel: The Delta Anomaly)