The Arachen are an alien species. In 896.M40, they rejected an appeal by the Golden Ambassador to join the Tau Empire, instead driving the Tau from their territory. What followed was a brutal multi-year conflict known as the Veil War, as the Tau and Arachen fought for control of the Western Veil. Ultimately, a young Commander Farsight was able to assassinate the Arachen leadership, known as the Arachen Trinity as Commander Dawnstone was launching a final offensive. The plan worked, and the Arachen were driven from the Western Veil forever.
Male Arachen are noted for having blade-like legs and were capable of fighting with bizarre but deadly martial arts, and they traveled through space in cocoon-like ships. Their nest-cities were designed as mazes, which made fighting through them extremely difficult.
- Oestromystics: Laid tangleclutch traps where unfortunate victims would be used to incubate egg-sacs.
- Grandfathers: Giant Arachens that ripped enemy warriors to pieces.
- Skitterlings: Small Arachens that attacked in swarms. They could penetrate inside Tau Battlesuits and eat their pilots from the inside out.
- 1: Codex: Tau Empire (6th Edition), pg. 28
- 2: Farsight Enclaves: A Codex: Tau Empire Supplement (E-Book) — A Warrior Born