So, I learned sometime that the Imperium of Man is divided into 5 Segmentum; Sol, Ultima, Tempestus, Pacificus and Obscurus.

I also know there are many sectors and sub-sectors in there. My first thought however was that just like the imperium is divided into 5 pieces, the rest of them would be divided in a similar fashion. A segmentum split into a few sectors here and there, perhaps only the more important places of them. And a sector divided into smaller sub-sectors.

I am now pretty sure this isn't the way it's done, reading something about how the Loki sector is in both the Ultima AND Tempestus segmentum. Also, as far as I understand, Ultramar is a sub-sector but doesn't belong to a specific sector? Am I missing something or am I right? Anyone got more specific details?

Thanks in advance

Oh, and also there is mention Systems and Regions as well..

The Tempestus segmentum has the Garon Nebula region, which is in the "southern" part of it, but also the Ophidium Gulf, which is mentioned as being south of the Tempestus segmentum, so outside the empire of man, correct?

The Sol Segmentum has the Sector Solar AND the Sol System… I guess the Sector Solar isn't simply our system, so I'd like to know what counts as a sector, system, region, sub-sector and so on.

Once again, thanks for any light on the situation

I'm fairly sure that there's vast swathes of space that don't come under any classification below Segmentum level. Places like the Gothic Sector aren't surrounded by neighbouring sectors but rather they are surrounded by decidedly empty wilderness space. Its only when an area becomes interesting by having planets, warp routes, astral phenomena and solar systems does anyone then bother with sector and sub-sector classifications. How they determine what counts as sectors and sub-sectors is beyond me, most likely, and in the finest traditions on of the Imperium, there isn't a standard. There's probably sectors in some Segmentums that would be classed sub-sectors in others and vice versa determined by the whim of the Crusade or Explorators that mapped them.

I could easily see an ambitious Crusade General/Admiral pushing to have an area he captured classified as a Sector to boost his renown. Or, on the other side of the coin, a Rogue Trader/Explorator, trying to play down the size of his discovery to keep the prize to himself for as long as possible.

DW

The heart of the matter is logistical, rather than anything else.

From the Imperial perspective (that is, the perspective of the Adeptus Terra, as the government of the Imperium of Man), the smallest discrete element of territory is the world.

An individual world is ruled over by an Imperial Commander - also sometimes known as a Planetary Governor - who rules that world on behalf of the Imperium. The Imperial Commander has basic obligations to the Imperium - the provision of a tithe of men and materials (the quantity and composition of which are determined in exacting detail by the Administratum), the collection of psykers, the maintenance of a standing armed force for planetary defence, and so forth.

A star system may or may not have multiple inhabited worlds. Where multiple inhabited worlds are present in one system, one of them will be regarded as the primary world, to which all others are beholden economically, spiritually, militarily and politically. The Imperial Commander of this primary world thus also has authority over the other inhabited worlds of the system.

Worlds are not, however, self-sufficient - they can be, but this is neither a requirement nor a defining factor. Multiple nearby worlds will be bonded by trade and mutual necessity in order to keep themselves supplied with essentials (food, potable water, raw materials, complex machinery, etc). An agri-world operates most efficiently with tractors and other machines to support the workforce, a hive world needs food for its populace and raw materials to produce machinery, and a mining world requires food to feed the miners and tools to gather materials… all three are interdependent.

The subsector can be viewed as an outgrowth of this concept - a cluster of nearby worlds, close enough that interstellar travel is not so long-winded, dangerous or arduous to allow for routine. As individual worlds cannot easily supply one another on a 1-for-1 basis, a complex network of interdependent worlds can form, particularly where one or more of those worlds produces a rare, valuable or unique resource. As with multi-world systems, one world in the subsector will be the capital, possessing authority and prominence over those around it.

A Sector, conceptually, is a cluster of several subsectors within a particular area - often defined as a cube a hundred light-years on a side. The stellar density within a Sector is immensely variable, leading to wildly-differing numbers of worlds per Sector depending on where you are in the galaxy and how established the Sector is. Within a Sector, individual subsectors will develop at their own pace, typically expanding outwards from the earliest colonisation attempts.

The most prosperous or otherwise prominent world within the Sector - typically a Hive or Fortress world, as they form a nexus of resource distribution and military power - becomes the Sector Capital. Sector Capitals are inevitably also subsector capitals, if only because it consolidates the logistics of the subsector and wider sector into one administrative entity.

Sectors are essentially autonomous entities - self-sustaining on a large scale, capable of significant military impetus (enough to support a crusade or territorial expansion), and able to exist independently of any external body save the Imperium itself. Each Sector maintains its own Imperial Navy Battlefleet (though these are nominally part of the Segmentae Battlefleets as well - for example, Battlefleet Armageddon is part of Battlefleet Solar), can muster untold trillions of Guardsmen, and possesses an extensive network of trade, religious and legal connections in the form of that sector's native Chartist Captains and embedded Adeptus Ministorum and Adeptus Arbites presence (whose structures parallel, but do not precisely mirror, the Adeptus Terra structures so far laid out).

The five Segmentae Majoris - Solar, Obscuras, Tempestus, Pacificus and Ultima - are the next level of authority, and only truly intervene in the matters of lower levels of organisation when utterly necessary. Few conflicts or crises ever expand beyond the potential capacity of a single Sector to deal with. When necessary, a crisis on a massive scale will be overseen by the office of the appropriate Master of the Segmentum (for the Calixis Sector, this is the Master of the Segmentum Obscuras, who commands from Cypra Mundi). The five Segmentum Capitals are Cypra Mundi (Segmentum Obscuras), Bakka (Segmentum Tempestus), Kar Duniash (Ultima Segmentum), Hydraphur (Segmentum Pacificus) and Mars (Segmentum Solar), and in each case these worlds are heavily-fortified worlds with massive manufacturing capabilities and extensive fleet yards (as always, Mars has the military and manufacturing infrastructure to support fleets and legions, while Terra is given over being the spiritual and metaphyiscal centre of the Imperium)

The Segmentae were originally defined for shipping and naval administration, but have expanded further in purpose as other organisations have taken advantage of the established infrastructure.

Ok… that took longer than expected. Hope it helps, though.

Awesome, now I know what I need to know

Also I know that space marine chapters worlds don't need to supply troops to the imperial guard, and there are some kind of inquisition planets that i presume are simply chosen for their location. But anyways I have a greater understanding of how it works now.

Thanks

It might help to envision the galaxy as a continant, the Imperium of Man as a large country, the five Segmentums as states that make up that country, Sectors as counties that subdivide those states, subsectors as districts within those counties, and individual planets as population centers within those districts.

N0-1_H3r3 had a pretty good write up for the more easily defined areas of Imperial space. When you start talking places with the titles of region or reach they are less well defined. Typically these areas describe a particular stellar feature rather than an administrative feature.

For instance the superfake region may be an area of space that regularly suffers predictable warp storms. This area may be inside or outside of Imperial space or possibly both. It could also span multiple sectors or be half in more than one segmentum. They don't have defined area's except in so far as that particular stellar phenomina occurs.

The best examples are the Halo Stars and the Eye of Terror.

Droma said:

The features you describe are more like astronomical/warp phenomena than defined regions of Imperial space. Segmentae, Sectors, Subsectors and worlds are all classifications of Imperial political divisions, rather than "geographical" regions, like the Eye of Terror. It's like the division between a nation on a political map and a mountain range on a purely geographical map.