"The worst of them all are the Space Wolves. They were animals, Great Terra, they were animals those things that fought with us. When you have sympathy with the enemy, you know you have the wrong kind of allies."
- — Combat Master Pawel Korine of the 40th Expeditionary Fleet of the Great Crusade
Thuyela was an Aeldari Craftworld of unrecorded but probably minor size that survived the Fall of the Aeldari and was encountered by the 40th Expeditionary Fleet of the Great Crusade at an unknown date in the late 30th Millennium, in an area of the galaxy simply designated as Kobolt space. It was utterly destroyed by the Space Wolves Space Marine Legion.
During the Great Crusade in the late 30th Millennium, the 40th Expeditionary Fleet encountered a race of unusually humanoid xenos in Kobolt space who were lethal and proud, and had no interest in human affairs. The xenos' base of operations was a great transparent vessel that sparkled as if it was made of glass, and so was nicknamed by them as "Scintilla City." It was in actuality an Aeldari Craftworld, and was called Thuyela in the Aeldari Lexicon.
True to their capricious nature, the Aeldari of Thuyela attacked the 40th Expeditionary Fleet without apparent reason or explanation, and managed to fight the Imperial fleet to a standstill. Fleet commanders called for the help of the Space Marines. An unrecorded number or Great Company of Space Wolves Astartes answered the call and quickly overcame the xenos.
As "Scintilla City" shattered around them, the desperate Aeldari realised that all would be lost if they continued to fight, and the xenos attempted to plead for terms. Imperial commanders involved in the action might have been content to naively negotiate a surrender, but the Space Wolves were not. Thuyela was sacked and its people slaughtered by the Space Wolves.
It was so completely destroyed that there was nothing left for the Imperial forces to recover or plunder. The fate of Thuyela's survivors, if any, is not recorded in Imperial records.
The senior mortal commanders of the 40th Expeditionary Fleet were so horrified by the incident that they were left with a disinclination to call upon the ferocity of the Space Wolves again, until they were forced to do so in the assault upon the Olamic Quietude homeworld not long after.
- Prospero Burns (Novel) by Dan Abnett, pg. 313