The homeworld of the fierce Chalnoth, a planet without government or law, which Jean-Luc Picard had visited while in command of the Stargazer.
Chalna is mentioned in the Next Generation episode Allegiance. One of Picard's fellow captives in the alien holding cell is Esoqq, a fanged Chalnoth warrior who explains with some pride that his people have no use for rulers and that he survives by his own strength.
Picard remarks that he went to Chalna twelve years earlier aboard the Stargazer, one of several details the prisoners compare while trying to work out why they were chosen. Esoqq cannot eat the food provided and warns that hunger may soon drive him to kill one of the others.
The captors turn out to be studying how different attitudes to authority interact, and anarchic Chalna supplies one extreme of the experiment.