The Imperium of Man

The galaxy is a vast spiral, ninety-thousand light years across and fifteen-thousand light years thick, containing hundreds of billions of stars. Only a fraction of those stars have habitable planetary systems, and only a tiny fraction of these have been investigated by Humanity or any other spacefaring race.

The initial human colonisation of the galaxy lies in the distant past, lost, forgotten, and obscured by twenty thousand years of regression and rebuilding. Human worlds are scattered throughout the galaxy, but their distribution is far from even. The greatest concentration of human worlds is in the galactic west, centred on the cradle of Humanity itself: sacred Terra. On the fringes of the galaxy, human worlds are few and often far apart.

Many human worlds benefit from mutual contact and a comparable level of technology. Others have regressed to a primitive and barbarous state as a result of long periods of isolation. New human-populated worlds are being discovered all the time, and there remains an unknown number which have been isolated and forgotten for hundreds, if not thousands of years.

The Segmentae Majoris

The Imperium is divided into five fleet zones known as the Segmentae Majoris. Although intended for purposes of fleet administration and shipping controls, the Segmentae have evolved into administrative divisions of the Adeptus Terra.

All shipping is supervised within the jurisdiction of one of the five Segmentae. Each Segmentum has a headquarters world called a Segmentum Fortress which forms the base of Imperial Navy operations within the Segmentum. The Segmentum Fortress is controlled directly by a high-ranking official of the Adeptus Terra known as a Lord High Admiral. The Segmentum fortresses are located at Mars for the Segmentum Solar, Kar Duniash in Ultima Segmentum, Bakka in Segmentum Tempestus, Hydraphur in Segmentum Pacificus, and Cypra Mundi in Segmentum Obscura.


Each Segmentum is divided into sectors varying in size according to local demands and stellar density. A typical sector might encompass seven million cubic light years, equivalent to a cube with sides almost 200 light-years long. The Imperium is not divided into a grid of sectors; rather, sectors are scattered throughout the vast reaches of the galaxy, forming small island chains of civilisation in the limitless ocean of the void. Sectors are connected to their neighbours by well-charted routes through the warp, but they are rarely adjacent and thousands of light years may separate one from the next.


Sectors are divided into sub-sectors, usually comprising between two and eight star systems within a ten-light-year radius, though some may encompass more systems. This size is governed by the practical patrol ranges of spaceships. Because sub-sectors are divisions of worlds rather than volumes of space, there are vast numbers of star systems within each sector, which do not fall within a sub-sector. These are referred to as inter-sectors, or more commonly as wilderness zones, forbidden zones, empty space, and frontier space. Inter-sectors may contain gas or dust nebulae, inaccessible areas, alien systems, unexplored systems, uninhabited systems, and uninhabitable worlds.

the Domains of the God-Emperor

Stellar empires can seldom be reckoned in terms of the spatial areas they occupy, but more often in terms of the star systems under their control. The Imperium is the largest empire in the galaxy, the million and more worlds that lie under its dominion spread throughout the entire galaxy. It extends to the limits of the Astronomican, the psychic beacon cast by the Emperor on Terra by which human vessels navigate. The Imperium cannot hope to control all of the star systems within this vast area, not even the majority of the inhabited systems within its borders. The galaxy also contains many alien races ruling smaller empires of their own, as well as empires ruled by humans who (often foolishly) consider themselves apart from the rule of Terra.

The Fringes

The fringes lie beyond the light of the Astronomican and so beyond the easy reach of the Imperium’s forces. They are known to contain human planets settled in ancient times as well as many alien worlds. Some of these planets have populations which are feral or barbarous, but many shelter highly advanced cultures. Most worlds are self-governing or belong to small independent human or alien empires. Agents of the Imperium are continually exploring the fringes, spying out dangers, and fighting wars beyond the borders of the Imperium itself.

The Halo Stars

Beyond the Fringes lie the Halo Stars. The entire galaxy is ringed with a halo of the most ancient stars, the majority nigh extinguished and circled by long-dead worlds. The desiccated secrets and horrors lie entombed beneath the surfaces of these worlds are best left unexplored. Few visit these regions, and even Rogue Traders often steer clear.

Wilderness Space

Most of the stars in the galaxy remain uncharted, their systems unexplored. Whole areas of the galaxy are embroiled within warpstorms and are therefore inaccessible from other areas. Other systems are simply remote and await mapping and codification by the Imperium’s explorator fleets. These largely unknown zones are known as wilderness space or wilderness zones. As warpstorms abate, previously inaccessible regions are explored, uncovering ancient human settlements as well as alien races and empires. Wilderness zones are spread throughout the galaxy, often separating more densely populated regions of space.

Alien Worlds

Humanity is but one of many races in the galaxy. However, few are so widely distributed or so numerous as humans. Most occupy only a single world or planetary system. The majority of aliens are comparatively primitive, peaceful or powerless, and of little interest to Humanity. Only a few alien races are powerful, aggressive and possess technology that rivals that of the Imperium. Among the most common are Orks and Eldar, though many more exist.

Planetary Governance

The worlds of the Imperium are governed by hereditary rulers called Imperial Commanders or Planetary Governors. The Imperial Commander holds his planet or system on behalf of the Emperor. In return for his oath of loyalty and regular planetary tithes, he controls the planet as his own. The Imperial Commander is free to administrate and defend his planet as he sees fit. Most worlds maintain fleets of interplanetary spacecraft — ships built to operate within their home system and in the vast majority of cases lacking the warp engines needed for travel between stars.

Interplanetary spacecraft are common on all technically advanced worlds. Even on primitive or feral worlds, the planet’s governor and his associated staff and warriors would have access to spacecraft — the general population would remain either ignorant of or completely in awe of spacecraft and technology.

Interplanetary shipping is administered by the Imperial Commander of each system. Some Imperial Commanders keep a tight leash on space travel, while others are far more lax and allow the organisation and maintenance of independent space fleets to serve the system. Similarly, while some Imperial Commanders police their systems very thoroughly, others find it impossible or impractical to enforce controls on independent operatives. Some Imperial Commanders undoubtedly collude with anarchic or piratical groups, trading off the control of planets or asteroids, mining or transport rights, or even defence and policing concessions, in return for personal profit. These commanders may maintain that this is the only way they can control their worlds.

Each planet is responsible for its own defence. Imperial Commanders are obliged to build ground-based defences, spaceports, and what defence fleets they can. The number of weapons and ships in any individual system will vary, depending on the enthusiasm of its governor as much as the possible danger. In addition to ships under the control of the Imperial Commander, planets lying in vulnerable positions or having a history of trouble may also have an Imperial Navy base. Although Imperial Navy ships are independent of those of the Imperial Commander, both would be ready to meet an emergency. Imperial Navy ships may also be stationed in one system so that they can patrol a number of nearby star systems.

Planets of the Imperium

The worlds claimed by the Imperium of Man are as diverse as the galaxy itself. Generally, only those planets that can support humanity, or be terraformed so they become habitable, are heavily settled, yet there are plenty of worlds where humans cling to life against nigh-impossible odds. Such worlds are those with natural resources of great value to the Imperium, or ones occupying a strategically vital location, perhaps near one end of a warp portal. In many cases, a tiny settlement might have existed for millennia, long forgotten or isolated, its inhabitants clinging on to a brutal subsistence level of life.

For convenience, the Adeptus Terra classifies the worlds of the Imperium into one or more broad types. In most cases these classifications describe the use to which the planet is put by the Imperium, while some describe the environment where this defines type. The sprawling bureaucracy of the Adeptus Terra classifies and sub-classifies planets according to a nigh-impenetrable system, often combining several features. Thus, a planet might be classified as a Hive World, because it is defined by its vast cities and astronomical industrial output, but its might also have as a secondary classification: Night World, Ocean World, or even Death World.

The major classifications are as follows:

Hive Worlds

The surfaces of Hive Worlds are generally inhospitable, even deadly, to human life after centuries of industrial processing. Urban conglomerations called hives, many miles in height, are the principle population centres. Factory, mining, and atmosphere processing are main industries, and the worker-populations are only maintained by a high import/export ratio, with the main import being foodstuffs and fresh water.


Agri-Worlds are almost entirely given over to the cultivation of crops, hydroponics, animal fodder, or animal husbandry. They have few conurbations, with the population spread widely across the planet’s surface. They are often clustered around Hive Worlds, who cannot survive without the constant supply of food. Some Agri-Worlds are almost entirely serviced by slave-serfs, servitors, or ancient machinery, and some are so thinly populated that only a single company of troops are stationed there as deterrence against pirate attack.

Civilized Worlds

The majority of the Imperium’s worlds are listed in this category, though the term could be misleading, for even on those worlds not touched by outright war in generations, most subjects carry firearms. Civilised Worlds are generally self-sufficient, possess starports, and are able to defend themselves against most threats they might be expected to face. Most of these worlds are further categorised as Cardinal Worlds, Garden Worlds, Mining Worlds, or any other of a thousand classifications.

Dead Worlds

Mankind has ever found the galaxy strewn with worlds with minimal, even non-existent, life traces, yet possessing clear signs of once having harboured civilisation. This often appears to be the result of ecological catastrophe or devastating internecine war, yet no Imperial or alien cause is discernable.

Death Worlds

Death Worlds are planets which are too dangerous to support widespread human settlement. The environments vary from world-wide jungles harbouring carnivorous plants and animals to barren rockscapes strewn with volcanoes and wracked by ion storms. These worlds are nearly impossible to colonise but must be properly explored — which necessitates the provision of outposts and other facilities. Some harbour rich mineral, vegetable, animal, or gaseous resources, and the Imperial Guard greatly values troops raised from these harsh places.

Research Stations

This category includes wide variety of locations, such as orbital stations, asteroid emplacements, and major facilities on Dead Worlds, Death Worlds, or on other planets. They are responsible for a wide variety of research, from animal breeding and domestication to weapons testing and gene-engineering. They also serve as listening and watch posts for planetary and system defence of major planets.

Feudal Worlds

The word ‘feudal’ refers not to a political system, for the entire Imperium is administered according to a feudal system, but instead to the world’s technical base, which will be just prior or just post-black powder. This may be the case because the planet has been cut off by warp storms for many centuries and regressed in the meantime, or its society might be rebuilding following a long period of war or some other form of planet-wide disaster. In general, the Imperium will allow such worlds to progress at their own pace, and it may be many centuries until a Feudal World progresses to a level similar to the bulk of the Imperium.

Forge Worlds

Forge Worlds are the sovereign domains of the Adeptus Mechanicus, and most take the form of planet-wide factories. A Forge World often also serves as a base of operations for one of the Titan Legions. Forge worlds are essential for the supply of arms and armour to the Imperium’s combat forces.

The Imperium of Man

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