Kaelor is an extremely isolated Craftworld of the Eldar. Under unclear circumstances, at some point in the distant past Kaelor made a webway jump to the edge of the galaxy and has not ventured back towards the galactic centre for several millennia. It has virtually no contact with the outside galaxy, and even the Harlequins barely remember its existence. Kaelor is known to pass through the Calixis Sector, a region normally avoided by the Eldar, every thousand years and is off limits by order of the Inquisition.
Craftworld Kaelor and the Current Campaign
Through the details of his interaction with the Eldar are unknown, Inquisitor Sand is known to be quite knowledgable about the ways of the Eldar, particularly Craftworld Kaelor. He is fluent (as much as a human can be) in the Eldar langauge and is familar with the use of some Eldar weapons and equipment. Speculation is that Sand has done extensive research on the Eldar and may have at one time spent time with members of Craftworld Kaelor.
The interactions of Inquisitor Sand’s Acolytes with the Eldar of Craftworld Kaelor on the other hand have been quite limited (in fact, only one recorded interaction) and this incident was not the most productive of encounters. Tasked to support a Deathwatch Kill-team with an assault on a secret base in the forbidden Threnos System, the Kill-team and Acolytes got involved in failed negotiations with Dire Avengers of Craftworld Kaelor that were sent to retrieve a wayward Bonesinger. The forces of the Imperium had secured the Bonesinger as a prisoner and were not going to turn him over to the Eldar. A firefight broke out in which the Bonesinger and the Dire Avengers’ Exarch was killed; the rest of the Eldar escaped via the Webway.