Dark Eldar is the name given to the Eldar that have spit on the traditions of their kin. Normaly viewed as pirates and slavers of the worst sort, the Dark Eldar ply the astral plane looking for other sites to plunder, plunder that is both treasure and beings that they use for both their dark arts and even darker games.
The Dark Eldar have one city, it is known as Commorragh, which means City of Hope and Darkness that is the Center of all. Commorragh is divided into many sections as the Dark Eldar war bands all claim areas that they defend to the utmost. These area are where the Dark Eldar cults all work to further their own aims.
It seems that even as the eldar fled to the astral plane, some of them where different, those that became the Eldar fled to the craftworlds, the others, those of a somewhat darker view point, became what is today called the Dark Eldar. Commorragh is a dark city, filled with