Mandalorians
A Mandalorian is a member of a group of masked warrior clans in the Star Wars universe. Mandalorians are less of a species, and more of a culture: they assimilate new species into their own existing culture when they conquer a planet or people. The leader of the Mandalorians typically takes on the title of "Mandalore". Mandalorians are frequently allied with the Sith Order, most notably Exar Kun and much later as a prototype for the clone troopers under the power of Darth Sidious and the Galactic Republic. In Star Wars: Knights of the Old Republic II: The Sith Lords the Mandalorians are allied with a jedi. The main Mandalorian clan is Clan Ordo. Mandalore stays on the Onderon's jungle moon, Dxun. In Star Wars: Knights of the Old Republic, there is a bounty hunter named Canderous Ordo, who in Star Wars: Knights of the Old Republic II: The Sith Lords is revealed through implications throughout the game and a final use of his name by Kreia during the ending sequence, to have become the new Mandalore. But, there are Mandalorian clans spread out on other planets, such as Dantooine.
History
Ancient Times/The Mandalorian Wars
Originally, the Mandalorian clans were led by the warlord "Mandalore the First" and were ranked amongst the best fighters in the galaxy, thriving on battle. They were known for their use of cutting-edge weaponry and held to a strict code of honor. They were a warrior race. These Mandalorians wore crusader armor that differed from one soldier to the next.
Mandalore itself is a temperate, albeit desolate, world located in a rather overlooked and inconspicuous area at the edge of the Inner Rim. Making a living upon its surface took on a battle of survival, and thus, the Mandalorians know no other way of succession. Most importantly, however, is the rare metal that is only found on this planet to date. It is called Mandametal and is one of the few known substances that can resist the focused energy output of a weapon such as a lightsaber (the others being cortosis ore and phrik alloy). Indeed, it takes an enormous amount of power and a proper strike with a lightsaber, not to mention a skilled Jedi who is strong in the Force, to penetrate a hole or opening through it, and the armor that nearly every Mandalorian began wearing is made of it. For their own single combat engagements, blasters and other firearms were forbidden; they were useless anyway. It came down to either finding a seam or soft spot in the armor and stabbing, or bludgeoning the opponent to submission or death. In addition, the metal is so dense that it actually can blunt a Force impression through it.
The Neo-Crusaders were led by "Mandalore the Ultimate" and started the Mandalorian Wars. The Neo-Crusaders armor was more advanced and uniform-like than their old armor. It came in many colors, though most were blue. Elites, sergeants, and a few other ranks wore green. Captains (and other ranks) wore red. Some other ranks wore yellow. The one who achieved the rank of Mandalore would wear a unique suit of armor.
After their defeat in the Mandalorian Wars at the hands of the Jedi Revan and Malak, Mandalorian society was slowly reformed, gradually evolving and changing into a culture of mercenaries, highly skilled soldiers for hire, rather than conquerors. Revan later told his friend Canderous Ordo to unite the Mandalorians after he left for the Unknown Regions. As detailed in Knights of the Old Republic II: The Sith Lords, Ordo took up the mantle of "Mandalore" and attempted to secretly gather a Mandalorian army, during this course of time he joined the Jedi Exile on her quest, which ultimately brought them to the destryed world of Malachor V. It is unknown if Canderous Ordo survived, but it seems likely that he did, due to the fact that Kreia's premonition claiming that he had many battles left to fight.
Some one hundred years before the Battle of Ruusan, the leader of the Mandalorians was assassinated by the bounty hunter Durge. The Mandalorians struck back and inflicted terrible vengeance upon the bounty hunter, but he managed to escape.
Late Republic / Early Imperial Times
Over the next few centuries the Mandalorians slowly transformed into a less clan-based, more mercenary-oriented culture. It was around this time that a schism occurred in their ranks. A violent splinter group, known as the Mandalorian Death Watch, revolted against the leadership of Jaster Mereel, who led the True Mandalorian loyalist faction.
Eventually the civil war between these groups spilled on to the pastoral world of Concord Dawn. Here the Death Watch leader Vizsla attempted to murder Jaster. However, thanks to the assistance of a young orphan named Jango Fett, Jaster and his followers escaped the trap.
Eventually, Viszla caught up to Jaster and the Mandalorians on a distant world and, thanks to the treachery of fellow Mandalorian Montross, Jaster Mereel was killed in battle.
Jaster's protege, Jango, took over the reins of leadership, despite Montross's disparaging comment that it would mean a "child leading them."
Jango's tenure as Mandalorian leader ended at the Battle of Galidraan, where a Jedi taskforce under the leadership of Master Dooku led to the death of every remaining Mandalorian, except for Jango.
After this disaster, the Mandalorians were effectively ended as a force in the galaxy. Individuals survived both on Mandalore and in other isolated pockets of known space, but they played little influence on galactic affairs until the Clone Wars, when Jango Fett became the genetic template for a Grand Army of the Republic. One clone trooper, an elite ARC trooper named Alpha-Ø2, ended up going rogue and changing the Mandalorians forever.
During the Clone Wars, the Mandalorians were employed as assassins by the Sith in their action to eradicate the Jedi, since the Mandalorians, inside their personal body armor, were impervious and uncorruptable. Jedi were subdued and placed aboard barges lined with Mandametal, to be towed out into empty space and dispatched - their true fates are not recorded.
Through some fluke of the Kaminoans' cloning technology, Alpha-2 had memories of Jango Fett. He went to Mandalore and started rebuilding the Mandalorian supercommandos from Mandalorian Protectors, police, and even Death Watchmen. Alpha-2 became Mandalore the Resurrector and his forces fought for Confederacy of Independent Systems. Among his troopers were Tobbi Dala and future Mandalore Fenn Shysa.
The words of several EU characters imply that the Mandalorian legacy will fade into nothingness in time, but also that their culture of strength and tenacity will not let it happen quickly or easily.
Post-Imperial Times
Twenty-six years after the Battle of Endor, the Mandalorians got a new leader, Boba Fett, who became Mandalore after Shysa's death on the planet Shogun and continued the tradition of leading the Mandalorian Protectors. During the Yuuzhan Vong War, Fett led the Mandalorians in the defense of Mandalore and liberated numerous planets like Tholatin and Gyndine.
But in all, the fates of the Mandalorians themselves are not recorded either. All that is known among the galactic populace is that the Mandalorians did exist, but that no known individuals walk among them any more. All of their technology was erased, and records are incomplete as to the exact location of Mandalore at the present time. During the peak of Mandalorian culture, one of their production factories, Mandalmotors, spawned branch plants on a few other planets, and this corporation continues to operate in limited capacity. Only two known examples of the Mandalorian battle armor exist as well, worn by the bounty hunters Boba Fett and Jodo Kast. Fett killed Kast for imitating him and soiling his name. Fett is thought to have received his armor off the battlefield of Geonosis, taking it from his father's, Jango Fett, corpse. Jodo Kast procured his armor when he killed the Mandallian Giant bounty hunter, Feskitt Bobb, whose suit of Mandalorian armor made Kast initially mistake him for Fett.