The Chenari were a species who were saved from extinction through the actions of James T. Kirk many years prior to the end of his five-year mission in command of the USS Enterprise.
In 2378, Icheb included this information, along with Kirk's encounters with the Pelosians and the Baezians, in his final report to Captain Kathryn Janeway, as part of the Early Starfleet History course of his Academy training. (VOY: "Q2")
This species was only mentioned in dialogue.
Details of Kirk's encounter with the Chenari are detailed in the Pocket TOS novel The Captain's Oath.