This archive tracks four layers. A record present in 3 of them (HH, M41, IND) is silent in the rest, and says so.
The Horus HeresyM30–M31
imperium
Industrial world that withheld its regiments
An industrial world of manufactoria that supplied arms to the Great Crusade and, when the Horus Heresy came, refused to send the Emperor its regiments, keeping its people on the production lines. Its debt for that refusal is still being paid ten thousand years later.
Age of the ImperiumM32–M40
[RECORD LOST]
No record for this location in Age of the Imperium.
The 41st Millenniumpre-Rift
imperium
Industrial world; home of the Vostroyan Firstborn
Neither a hive world nor a forge world but something between: 9.3 billion people living and dying on the production lines of a bleak, polluted planet of harsh cold winds, ruled by the Techtriarchs. Under the Offering of the First Born the eldest son of every family serves in the Imperial Guard, and its Firstborn regiments, such as the 68th of Rebel Winter, are reinforced from home for as long as they last.
Era Indomituspost-Rift
imperiumImperium Nihilus
Industrial world cut off by the Great Rift
Cut off from the rest of the Imperium by the Great Rift, Vostroya raised more Firstborn regiments and sent them into the void all but blind, to find war zones and Imperials calling for help; many were lost in the dimmed light of the Astronomican.
Position
Map frame: 175, 250 in the archive's 0–1000 disk space (core at 500, 500).
Distance from the core: 410 units ≈ 43.6k light years, north-west of the galactic core.
Height above the disk plane: -0.5 units — invented thin-disk jitter, deterministic per record. No published source gives any location a z coordinate.
System: Vostroya System
Books set here
2 titles in the reading tracker touch this record. Titles link out to the tracker.
Every fact in this record, and where it came from. Editorial derivations say so.
book-joinhigh
wh40k.lexicanum.com/wiki/Vostroya (read directly in a browser on 2026-10-01): its sources list cites Rebel Winter (Novel) chs 2, 3, 5, 11 and 15 for the world's culture, terms and hives (Hive Ahropol, Hive Tzurka, the regions of the Magdan, Sohlsvod and Muskha). Joined as 'mentioned': the 68th Firstborn's homeworld is talked about throughout and never visited; the novel is set on Danik's World.
segmentumhigh
wh40k.lexicanum.com/wiki/Vostroya infobox 'Segmentum: Segmentum Obscurus' and lead 'located in Segmentum Obscurus beyond the Eye of Terror', both cited to Codex: Imperial Guard (5th Edition) pg. 18 and pgs. 26-27 ('A Galaxy At War'). NAME-COLLISION CHECK: Lexicanum's search for 'Vostroya' returns one world ('Vostroyan' redirects to it); no other index record uses the name.
classmedium
'hive' from what the page says it LOOKS like: an Industrial World, 'technically neither a hive world nor a forge world' but in between, 9.3 billion people in manufactoria and hives (Ahropol, Decius, Tzurka), a landscape 'extremely bleak - highly polluted', harsh cold winds, the cold north and south uninhabitable. This dataset has no industrial palette; 'hive' (dense city sprawl and city light) is the nearer of the two the page itself names, and 'forge' was refused because the world is not a Mechanicus forge (it is ruled jointly by the Techtriarchs).
gposlow
inferred: region-level. The segmentum is published and so is a relation: 'beyond the Eye of Terror' (Lexicanum Vostroya, citing Codex: Imperial Guard 5th ed.). Placed at [175, 250], 50 units north of the Eye of Terror feature's centre [180, 300] (outside its 29-unit radius) and further from Terra than the Eye is (280 against 230 units), inside the stylised 'obscurus' polygon (checked) and 31.4 units from Medusa, the nearest Eye-side record, so both stay selectable. The magnitude past the Eye is editorial. The point falls on the Nihilus side of the greatRift spline, which agrees with Lexicanum Vostroyan_Firstborn: Vostroya 'was cut off from the rest of the Imperium by the Great Rift in M42'. Z -0.5 from compute-z.mjs under zPolicy.
erashigh
wh40k.lexicanum.com/wiki/Vostroya hh from ('During the Horus Heresy, Vostroya refused to provide regiments to the Emperor', Codex: Imperial Guard 5th ed. pg. 18). m41 from https://wh40k.lexicanum.com/wiki/Vostroya (Industrial World, ~9.3 billion, Techtriarchs, bleak and polluted) and https://wh40k.lexicanum.com/wiki/Vostroyan_Firstborn (the Offering of the First Born). indomitus from https://wh40k.lexicanum.com/wiki/Vostroyan_Firstborn ('when Vostroya was cut off from the rest of the Imperium by the Great Rift in M42, more Vostroyan Firstborn regiments were raised and sent into the void mostly blind'); riftSide 'nihilus' agrees with the spline. aoi is not carried: no tracked book names the world then.
systemIdhigh
'vostroya' from Lexicanum's infobox 'System: Vostroya'. No survey is authored: the world is only mentioned in a tracked book. Lexicanum names one moon, Turtolsky (White Dwarf 317), the start of a survey if a book is ever set there.