an-Jirok was a dissident group on Altair VI which launched a coup against the Altair government in 2348. During that coup, Starfleet Ensign Manojlovich, assistant chief of security of the USS Lexington, plus four other Lexington guards, were killed.
The an-Jirok ruled Altair VI until 2351, at which time the former system of government was restored. (DS9 - The Brave and the Bold, Book One novella: The Second Artifact)