Craftworld Catumen is the self acclaimed ambassador of the Eldar Race across the stars. They believe in peaceful relations with the Xenos where one can find them, and where one can not beat the enemy. They are a relatively small Craftworld, both in size and people, and rely upon the other Craftworlds and members of the Eldar race for their continued existence most of the time. The Herald Council acts as a senate for different cultures of the race, though they are all but nominal in their position as many other Craftworlds have influence over the happenings of Catumen.
The history of Catumen began during the late years of Great Crusade, as an idea inside the minds of the Council of Iyanden. The Council prepared a sattelite Craftworld, one that would be the ambassador of Iyanden in the galaxy, representing them. For a time it worked, as Catumen carried the Light of Iyanden across the stars to xenos and Exodite, bringing them word of the inheritor of the Eldar people. But as time went on and Iyanden's power waned, the Craftworld looked for more supporters. Biel-tan was the first, sending soldiers to protect the Craftworld. Ulthwe came second, sending Seers to provide for the guidance. Alaitoc came third, and brought her people. Soon nearly all had given some to the Catumen, and all held a moniker of power over the Herald Council. Exodites were invited to partake in it, and Harlequins of the Webway. Only in the late 39th millenium the Dark Eldar joined, in the form of Shrine of the Darkfire led by Hierarch Zaine. Eldar Corsairs came and went, but they were part of it more than they were not.