The Artio-Luth, the Dunlending Bear Clan, were a loose group of Dunland-based peoples who shared Beorning blood. Though unable to transform into bears, their Skin-changer blood made them prone to terrifying battle-furies and falling sicknesses- the "Warp Spasm"- a flaw that dogged them for much of their history.
The Artio-Luth were tall Men, averaging about 5 feet and 6 inches at the smallest. Their bodies were covered in brown, ruddy or black hair in large unkempt clumps. Their arms were long and beefy, and their legs likewise. This, overall, gave them the appearance of giants to a more civilized observer.
They wore furs, and often decorated their beards with bits of carved bone. They used woad and indigo for war paint, forgoing heavier armor. In battle, they preferred pattern-welded pikes, as to counter the horses of their hated enemies, the Rohirrim. They would also wield large two-handed axes, using them to smash apart and push aside the foe in the midst of battle.
Under great stress, the men of the Artio-Luth would unconsciously attempt to skin-change- instead causing their bodies to spasm uncontrollably, then fly into an uncontrollable fury. In this state, they abandoned any semblance of technique and finesse, striking out wildly at all in their path. Running along on all fours at breakneck speeds like wild beasts, they terrified and awed those who fought them.
Like all Dunlending clans, the Artio-Luth held a single spirit - a powerful child of the "Great Wheel" that made the universe- in great reverence, and called upon it in rituals. In their case, the Great Bear- the representative of martial strength, patience, and courage- watched over his "children" and granted them the gift of "war-rage".
The Artio-Luth's ancestors, a large and organized tribe of Dunlendings (from which the various clans sprung), roamed the plains of Dunland and the valleys of the White Mountains. But as the Rohirrim and the Numenoreans drove the Ur-Clan from it's lands for conquest, it began to split into clans and family groups who shared common totems. The ancestors of the Artio-Luth adopted the bear as their totem, and found themselves mixing with Beornings likewise driven.
This mix was not a entirely healthy one for the resulting people- they would find themselves shunned by other clans for their terrible rages and falling sicknesses. But, in a raid on the Rohirrim's capital of Edoras, one member of the Turch-Luth would taunt an unexpected arrival of several Artio-Luth warriors into their rages- and was promptly felled for his folly.
Wulf would make use of several Artio-Luth raiding parties during his war on the Rohirrim, employing them as a vanguard for his main force.