Codex/Galactic History 67: Mandalore the Ultimate

The Galactic History 67: Mandalore the Ultimate codex entry is located within the Achievements:Datacrons section of a player's codex once it has been unlocked.

Codex entry
"This datacron holds unheard of power and knowledge collected by an ancient race. You access its power and discover writings which are clearly only one small piece of a massive galactic history:

The Mandalorians had suffered not only defeat but humiliation in the Great Sith War. After their leader, Mandalore the Indomitable, crash-landed on Dxun and was devoured by wild beasts at the war's end, a new warrior rose to take his place, later called "Mandalore the Ultimate."

Deciding to bring in new blood, Mandalore opened the ranks of the Mandalorian Crusaders--once dominated by the followers of the ancient Taung, now fielding alien recruits. Calling themselves Neo-Crusaders, these warriors adopted traditional Mandalorian armor and training. Mandalore established a base on Dxun, testing his warriors against Dxun's infamous predators.

As their ranks grew, the Neo-Crusaders began to conquer worlds weakened in the Great Sith War. Later Jedi would believe Sith influences propelled the Mandalorians into war, but the Mandalorians themselves claimed to be driven only by the chance for conquest and revenge."