Thandros is an Imperial System, comprising the planet Thandros I and the binary Mining Worlds Thandros II and Thandros III, and is located in the Eastern Fringe to the galactic south-east of Ultramar.[2a]
A Telepathica Matrix orbited Thandros I, which boosted astropathic signals and allowed intragalactic communications. In 745.M41, Inquisitor Kryptman, after discovering the terrible fate of the planet Tyran at the hands of the advancing Hive Fleet Behemoth, attempted to send a message via Thandros's Telepathica Matrix. But he could not get through. In desperation he ventured to Thandros and found it destroyed, the Matrix found with its magazines empty and its laser banks burnt out. No help arrived for the feebly defended system as the Shadow in the Warp blocked any of their pleas. The workers of Thandros II and Thandros III were slaughtered in the own dark labyrinthine mines as the Swarmlord led the final attacks on the Thandros system.[2b] Kryptman managed to salvage the Matrix so it could project the valuable data-codex, that chronicled the Tyranid invasion of Tyran, along with his own report. The Ordo Xenos replied with orders to travel to Macragge and assist in mounting a defence against the alien fleet, which became the Battle for Macragge.