Far out on the frontiers of the galaxy, on the edge of explored space, lies the Alaitoc Craftworld. The Alaitoc Eldar are zealous in their guard against the touch of Slaanesh, even more so than other Eldar Craftworlds. The prescribed Eldar Paths are closely followed, and Eldar that eschew them (the so-called Outcasts) are looked down upon. However the strict confines of the Craftworld's ideology have caused some of its citizens to leave the ship and strike out on their own or in small groups as rangers, craving the freedom to explore and to experience the galaxy on their own terms. They return in times of need however, and so Alaitoc armies have a substantial force of rangers. These rangers are usually accompanied by harlequins, mysterious eldar that have no craftworld of their own, but instead travel through the webway to various craftworlds. Alaitoc armies also extensively use war walkers and prefer ranged weapons. The colour of Alaitoc armour varies from blue and yellow, to blue and bone.
The craftworld was subject to full-scale invasion by human forces from the Imperium of Man. A massive Imperial force with a large Navy fleet, Imperial Guard regiments, heavy armor, and Space Marines from the Sons of Orar Chapter attacked the huge vessel, and despite heavy casualties managed to establish a beachhead. The reason for the invasion apparently was the sacking of an Imperial civilian convoy by a group of Alaitoci rangers and Outcasts.
Read more about this topic: Eldar Craftworlds (Warhammer 40,000)