Quilboar are a primitive race of sentient boar humanoids that primarily live on the continents of Kalimdor and Kul Tiras. They are known for their aggressive nature, preference to live among clusters of large thorns, and their conflicts with the Tauren people in a region known as the Barrens.
Like all animal-based species on Azeroth, they originate from one of the wild gods, powerful manifestations of life and nature that most often take the form of powerful animals. For the quilboar, the wild god was a great boar named Agamaggan. He was a mighty fighter and was one of the wild gods called on by Cenarius during the War of the Ancients to join the night elf resistance and combat the invading demons of the Burning Legion.
Agamaggan, the great ancient boar during the War of the Ancients
During the war, Agamaggan was a powerful force to be reckoned with as he slew thousands of doomguards and felguards. Not only was his size and strength like that of a normal boar magnified, but he also was said to be able to breathe corrosive acid and project thorns from his back. While his power was great, he eventually fell to the sheer numbers of demons after a long battle that led him into the west sacrificing himself to allow Malfurion Stormrage and others to reach the Well of Eternity and prevent it from becoming a massive portal for the demon lord Sargeras.
As Agamaggan died, his body became the Razorfen, sprouting giant clusters of thorns and vines which would become something of the capital city of the quilboar, called a kraul. It is unknown exactly what connection the quilboar have to Agamaggan as to whether they are his children in some way or simply a race he created in his own image. In any case, his resting place of the Razorfen is revered by them as the “holiest of all thorn clusters”. They believe the entrance, the Razorfen Downs is made from his mount and that it will swallow whole those not loyal to him, and spit out their bodies.
The entrance to Razorfen, formed from the head of Agamaggan
As it just so happened, Razorfen is located in the middle of the Barrens, a region also inhabited by the tauren. The two races would clash for years until the arrival of the orcs led by Thrall who allied with the tauren and helped to tip the scales in their favor.
The Quilboar lived in numerous tribes spread around the region, overflowing into the tauren’s newly-settled region of Mulgore and the orc’s home region of Durotar. Strangely, at one point the Razorfen tribe entered into an alliance with the undead Scourge, allowing the lich Amnennar the Coldbringer to use Razorfen Downs as a Scourge stronghold. Amnennar had created the Death's Head tribe, a group of undead quilboars under his command. The Red Dragonflight, defenders of life and thus particularly devoted enemies of the undead Scourge, employed adventurers to stop the lich and cleanse Razorfen several times, but the lich kept coming back from his phylactery until it was at last taken into the dragonflight’s custody.
Amnennar the Coldbringer
After the Cataclysm, several quilboar tribes took advantage of the chaos to expand their territory and strike back against Horde holdings. However, they were driven back by counter-attacks from new Horde recruits who were able to kill the leaders of the invasions.
Around the same time, the leader of the Razorfen tribe, Charlga Razorflank, ordered her followers into attacking other races by convincing them they needed to revive Agamaggan and required blood to do it. However, Agamaggan's noble spirit appeared to adventurers and asked them to end Razorflank and her cronies as punishment for allying with the Scourge in the hopes that the quilboar could return to their noble roots without corruptive influence.
Of all forms of magic, quilboar have the strongest connection with shamanism. When a quilboar tribe settles a new region, their shamans seed and grow new roots for them to live in, which has the side-effect of scaring the land and choking out all other life in the region. They are also masters of geomancy and consider the reading and mastering of earth and stone to be the highest form of shamanism.
A quilboar geomancer from the Briarback tribe.
At this point, the quilboar fluctuate between being mere pests to slightly more serious threats but never range from anything the armies of the Horde can’t handle when their lands and cities are encroached on.