Sarum

Sarum is a Maelstrom-side hell-forge of the Dark Mechanicum, a barren world whose Crimson Priests armed the World Eaters through the Heresy. Angron 'rescued' then occupied Redjak's empire in the Golgothan Slaughter; Perturabo later found a bound Khorne daemon, Sa'ra'am, at its heart, and the first Obliterator walked out in Volk's armour. This is the sarum-system pin, not the civilised world tagged sarum-946.