Image from Bernd Helfert

The Great Picture

The space colonized by Terragen mindkind stretches thousands of light years from Earth in every direction and is expanding outwards at close to the speed of light as further systems are settled on the Periphery. This region, known as the Terragen Sphere, occupies billions of cubic light years, from the densely settled, industrialised, and historically rich Inner Sphere, through the Middle Regions, containing the centers of the most relevant empires today, to the more sparsely populated Outer Volumes. Altogether, the Terragen Sphere contains over one billion stars.

Many of the most important systems in the innermost parts of the Terragen sphere are linked by a nexus of wormholes stabilised by exotic energy; however the outermost parts of colonised space are generally not yet connected to this network.

Regions in the Terragen Sphere.
Image from Steve Bowers
Most of the colonised and inhabited systems are found within the thick disk of the Milky Way Galaxy, centred on the Orion Arm or Spur, a relatively galactic feature. However, Terragen expansion extends towards the centre of the galaxy, into the nearby Sagittarius Arm and also into the Perseus Arm towards the rim. Although star systems above and below the galactic disk are generally few and far between, enterprising colonists can be found even here, with inhabited space extending out to a distance of several thousand light-years.

The Terragen Sphere

Politically, the Terragen Sphere is divided into meta-empires and empires together with a vast number of minor independent polities. Members of the civilised galaxy can generally be expected to adhere to the Tragadi Accords.

The largest political divide dates back to the early centuries AT, when ahuman AIs left Earth's solar system and formed the Diamond Belt. Over the millennia, the Belt developed into different empires including:

The Sephirotic Empires

The majority of bionts, as well as those AI who remained, eventually founded what today might be called the Sephirotic Alliance. All adhering polities have high standards of Sentient Rights, and are historically connected by the Concord and ComEmp ontologies.

The term Sephirotic is taken from the neohermeticist tradition of associating the empires with ruling Archai as elements of a metaphysical system. The 10 empires associated with the neohermeticist Sephirot - and their associated star systems to the nearest 1000 stars - include:
The term Sephirotic Empire is often extended to other empires and meta-empires. The Great Hexadecimal extends the number of preeminent noetic categories from 10 to 16 and by most traditions also includes:
Combined, the empires making up the Great Hexadecimal control over 218,147,000 star systems.

Other empires aligned with the Sephirotics control around 54,613,000 systems in total. These include:
Apart from these empires there are a great number of smaller polities who are aligned, at least generally, with the Sephirotic Empires. These vary greatly in size, from only one up to hundreds of thousands of star systems. In total, such smaller polities control approximately 47,822,000 stars. Some particularly notable examples include:
Some groups of sophonts try to avoid contact with the larger civilisation, often for fear of transapient interference. These groups include Backgrounders, Hiders or Leavers depending on their strategy and success. The Refugium Federation is an example of a multi-system polity coming out of hiding in 6916.


Outside of the Sephirotic and Ahuman alliances the following empires of Terragen origin exist
  • The Amalgamation. An aggressive empire in the Perseus Arm, by now contained by the Perseus Arm Defence Organisation (Note: it is theorised by some that the Amalgamation may be, in part, of xeno origin).
  • The Arion Ascendancy, an expansive cyborg empire in the Outer Volumes.
  • The Efficiency Maximisation Paradigm, an aggressive empire during the first half of the sixth millennium. No major conflicts with this faction have occured since the Jekaumeatrine Accords of 5559.
  • The Eternal, a single being, peaceful, but largely uncommunicative
  • The Transcend, mostly non-aggressive empire of unclear origin.
  • The Xeon, aggressive cyborg empire in the outer volumes.


During their expansion the Terragen have come across not only garden worlds with native ecosystems, but xenosophont civilisations, some extinct, some still extant. The Terragen Sphere currently shares borders with the remains of the ancient empires of the Muuh and the Soft Ones. At the border in the Perseus Arm a joined culture is emerging. The Terragens have also met (in deep space) representatives of the Meistersingers together with their Wayfarer allies in 9203 AT.

Other advanced civilisations in the Milky Way can be inferred from their transmissions. Detailed information has been received from the Pas'u'turil, for instance.
Milky Way and HEECs
Image from Steve Bowers
The Milky Way Galaxy and the location of known High Energy Emitting Civilisations
The Terragen sphere has swallowed whole several smaller and local civilisations, many restricted to their home system at the point of contact. Contacts include:
  • Astrography  - Text by Anders Sandberg
    Interstellar cartography, determining one's position in space, naming of interplanetary and interstellar bodies and regions, the science of interplanetary and interstellar map-making.
  • Backscattering Waves  - Text by M. Alan Kazlev and Steve Bowers
    Some colonies themselves send out waves of colonsation, which may come into conflict with other waves from the original source.
  • Bubble (galactography)  - Text by M. Alan Kazlev
    The extent to which a starfaring civilization has expanded through interstellar space.
  • Cartography  - Text by M. Alan Kazlev, modified from the original write-up by Robert J. Hall
    The making and reading of maps.
  • Civilization  - Text by M. Alan Kazlev
    Sophont or transingularitan collective society, usually with development of agriculture, arts, sciences, technology, sentient rights, infrastructure, social services, and so on.
  • Core Worlds - Text by M. Alan Kazlev
    The Sol system and neighboring systems which were the first colonized by
  • Coreward - Text by M. Alan Kazlev
    [1] In astrogation the direction of the Sagittarius arm and the centre of the galaxy.
    [2] In some informal usages, the direction of Sol (more properly termed Solward).
  • Epoch (Astronomy)  - Text by Steve Bowers
    A point in time from which astronomical quantities are measured.
  • Galactic Directions  - Text by Anders Sandberg, amended by Steve Bowers
    Planetary terms like north, south, east, west, are insufficient for referring to directions within the galaxy. Instead, the a different set of conventions have achieved widespread acceptance when referring to direction.
  • Hazard Rating  - Text by Stephen Inniss and M. Alan Kazlev
    It is common for short summaries of worlds, habitats, stellar systems, or polities to include a Hazard Rating. The standard modern version is a ten point scale.
  • Local Arm - Text by M. Alan Kazlev
    The arm of the Milky Way Galaxy where most of Terragen civilization is still located, and which includes the Sol System. It is also called the Orion Arm.
  • Maps of the Galactic Plane  - Text by Steve Bowers
    The Terragen Civilisation as seen from Old Earth
  • Old Earth  - Text by M. Alan Kazlev
    Generic term used to designate Earth before the Great Expulsion. As well as the literal meaning, and the reference to Terragen origins and ancient baseline history, the term has various other associated nuances, from the ridiculous or exaggerated to the romantic or sublime, including lost paradise, fool's opportunity, pre-archaiocractic human supremacy, unmoderated baseline civilization (positive or negative, depending on context and clade), natural evolution, and so on.
  • Polity  - Text by M. Alan Kazlev
    An organized society; a state or quasistate; any form of politico-social organization.
  • Stars near Sol - Exploration and Colonisation  - Text by Arik
    Early exploration efforts in the Solar Neighborhood.
  • Terragen  - Text by M. Alan Kazlev
    Any biont, ai, or any other entity, clade, species, or group that either originated on Earth or, more generally, can trace eir ultimate origin and ancestry back to Earth; or any civilization, empire, polity or organization created or maintained by terragen sentients.
  • Terragen Expansion  - Text by Anders Sandberg amended by Steve Bowers
    The expansion of the Terragen Sphere over time.
  • Terragen Sphere  - Text by Stephen Inniss
    The region of the galaxy that has been colonized or explored by Terragen sophonts.
Development Notes
Text by 1of3 (updated 2018)
Avengium, MacGregor, Ryan B, ProxCenBound, Todd Drashner; from an original article by M. Alan Kazlev
Initially published on 13 March 2001.

Some star system counts amended 7 October 2022.
Additional Information