What does Legion, Thebian mean in the Bible?

Dictionary

Charles Buck Theological Dictionary - Legion, Thebian
A name given, in the time of Dioclesian, to a whole legion of Christians, consisting of more than six thousand men, who were said to have suffered martyrdom by the order of Maximian. Though this story had never wanted patrons, yet it is disbelieved by many. Dr. Jortin, in his usual facetious way, says, that it stands upon the authority of one Eucherius, bishop of Lyons, and a writer of the fifth century, who had it from the Theodorus, another bishop who had the honour and felicity to find the reliques of these martyrs by revelation, and perhaps by the smell of the bones!