Alien Species


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Fire Caste
General Information
Scientific name Tau Tau
Homeworld T'au
Habitat Desert Plains (Origin).
Height Roughly Human
Diet Herbivores
Sapience Level Sapient
Language Tau
Subspecies/Races Various Castes
Behind the Scenes
Universe Warhammer 40k

The Insignia of the Tau Empire.

The Tau Empire is a rapidly expanding alien stellar empire situated within the Imperium's Ultima Segmentum, near the Eastern Fringes of the Milky Way Galaxy. The Tau Empire was founded by the Tau caste called the Ethereals, who lead the Tau Empire in the name of the philosophy they have named the Greater Good. Several intelligent alien races (the Kroot, Vespid, Nicassar, and the Demiurg) have allied themselves with the Tau. The Tau Empire borders the Imperium of Man, and lies within the reach of the Astronomican. It has suffered many raids from the Orks, and also seems to lie in the path of several Tyranid splinter fleets of Hive Fleet Kraken.


The exact date of founding of the Tau Empire in the Imperial Calendar is unclear, however the way in which the Tau were united as a species is a well-known tale. What is known is that only 6,000 standard years ago, in the 35th Millennium, an Adeptus Mechanicus Explorator fleet had discovered the Tau homeworld of T'au and determined that its population of sentient xenos were a primitive people at the Stone Age level of development who had only just mastered fire. They have developed very rapidly as a space-faring species.

Earlier in their history, the Tau were a culture built upon warring tribes. During this time, the Tau's legends tell of the first appearance of the Ethereals at the city of Fio'taun. The fortress city of Fio'taun was under assault by the Tau warriors from the plains. Though negotiation had been attempted, the fierce plains warriors would settle for nothing less than the annhilliation of the city of Fio'taun. For five long Tau years the inhabitants held off the savage assaults with their thick walls and plentiful cannon. However, disease and starvation began to take their toll. As the tide of the siege turned, two mysterious Tau appeared. One made his way into the camp of the plains Tau, exuding a quiet authority that no Tau was able to resist. Soon, the leader of the plains warriors was persuaded to parley with the settled Tau of Fio'taun. Similarly, the other mysterious Tau made his way deep into the fortress. Within a few short hours, the gates stood wide open, and the Tau of both sides stood ready to talk.

The Ethereals spoke of the importance of peace and understanding between all Tau. They described a Greater Good that each Tau must strive towards. The besiegers and the besieged quickly agreed with the Ethereals and a truce was reached. Across the world of T'au, Ethereals emerged, each with the same quiet authority and message of harmony and cooperation. With the Tau united, they were able to rapidly develop their civilization's technology, ultimately attaining faster-than-light spacefaring capabilities.

The Tau Empire soon expanded its borders through a series of Expansion Phases. The Tau empire has gone through 3 phases of expansion as of the turn of the 42nd Millennium. These phases are marked by Tau military campaigns during which nearby worlds are colonized, conquered, or sometimes peacefully persuaded to join the Greater Good through diplomacy and a manifest demonstration of the benefits provided by advanced Tau technology.

Therefore, apart from the star systems directly colonised by the Tau, which are called Septs, the Empire also includes the worlds and star systems belonging to the species of the Kroot, Vespid, and the Nicassar. It is currently unknown if the Demiurg are full members of the Empire, allies, or mere trading partners. The Tau Empire is composed of over twenty fully-developed Septs and around one hundred settled worlds, but the exact number and most of their names are unknown to the Imperium.

A known splinter faction among the Tau are the Farsight Enclaves founded in the Damocles Gulf by the Tau Commander Farsight against the orders of the Ethereals. Also, more recently, some worlds and star systems of the Imperium of Man have been conquered by the forces of the Tau, while a handful have seceded from the Imperium and pledged their allegiance to the Tau Empire.

At some point, the Tau sent an expeditionary force to the Imperial planet Malbrede where they came into conflict with the Ultramarines Space Marine Chapter in 936.M41. However, the planet proved to be a cursed Tomb World when the fighting of the Tau and the Ultramarines awakened the sleeping Necrons from their tomb beneath the surface. In an effort to combat this terrible threat to both races, the Tau and the Ultramarines combined their forces to defeat the Necrons. Once the conflict was over, the Tau were allowed to evacuvate their forces by the Ultramarines Chapter Master Marneus Calgar who proceeded to destroy Malbrede through the use of an Exterminatus order.

In 966.M41, the Tau fought against the Adeptus Astartes of the Space Wolves Chapter during the War for Kvarium Alpha. On that water world, the Space Wolves' drop pods landed deep in the oceans where their occupants, their Power Armour altered by Space Wolf Techmarines to operate in undersea environments, made a move to engage their enemy. On the surface, the battle was fought between the two sides with an equally deadly conflict erupting in the depths of the sea between the Space Wolves and Tau Battlesuits. Thunderhawk gunships armed with torpedoes, prop-bombs and missiles were used to great effect against the Tau's Hammerhead tanks and Manta gunships. Ultimately, the Space Wolves proved to be the victor in the conflict, though hundreds of Tau and Space Wolf corpses floated to the surface. With their mission complete, the Space Wolves made the long trek back to land across the sea bed.

Hive Fleet GorgonEdit

The Tau Empire was invaded by the Tyranid Hive Fleet Gorgon, a splinter fleet of the much larger Hive Fleet Behemoth, in 899.M41. The Tyranids of Hive Fleet Gorgon were exceptional for their ability to quickly adapt on a biological level to new circumstances of battle, such as evolving immunities to the Tau's energy-based weaponry. This rapid pace of defensive adaptation may have been unique to the Tyranid breeds of Hive Fleet Gorgon, or it may have been a response to conflict with the Tau, who are also a highly adaptable species, but on a technological rather than biological level. The combined forces of the Tau and the Imperial Guard destroyed Hive Fleet Gorgon in 903.M41, albeit after both humanity and the Tau lost several colony worlds to the rapacious Tyranids.

Tau SocietyEdit

Each alien race within the Tau Empire has a unique and different culture and society. However, all of the Tau Empire's races hold a common belief in the Greater Good that binds them together.


Tau society is centred around the philosophical concept of the Greater Good, where individual Tau sacrifice their personal gain in favour of benefiting the Tau Empire as a whole. It is from this philosophy that the Tau's all-purpose motto, "For the Greater Good!", is derived. The Tau castes, although different in role and organisation, work together for the benefit of all Tau: the Earth Caste provide and produce, the Water Caste communicate and distribute, the Air Caste connect the worlds of the Tau Empire, and the Fire Caste protects and defends all the others. The external image the Tau project towards other species is that they are enlightened, altruistic and idealistic, believing in the unification of all "for the Greater Good".

Tau society is divided into five castes:

  • Fire Caste - The military ground forces of the Tau Empire
  • Earth Caste - The engineers, laborers and scientists of Tau society
  • Water Caste - The diplomats, storytellers, administrators and bureaucrats of Tau society
  • Air Caste - The pilots and officers of the Tau Navy
  • Ethreal Caste - The political and religious leaders of the Tau Empire


Kroot society is divided into tribes, known as Kindreds. Each Kindred is an extended family group of Kroot and is led by a Shaper, one Kroot with an intuitive understanding of the DNA absorption process all Kroot possess, and responsible for guiding the evolution of their Kindred. The Shaper, upon identifying a beneficial genetic trait, will instruct his Kindred to hunt and consume that animal, and then control the breeding of the Kindred to ensure that the offspring are born with the selected trait. Often, Kindreds will band together, and the Shapers will form a Council, of which the most influential Kindred's Shaper will be made leader of the entire group. On rare occasions, a Chief will unite a large number of Kindreds underneath him. Kroot dwell in warm, temperate conditions on the worlds they inhabit, and construct large tree houses from animal hides, bound together by regurgitated dead wood. Some Kindreds reside in the ruins of the Imperium's hive cities on former human worlds conquered by the Tau Empire. The consumption of flesh is one of the key tenets of Kroot spirituality, as it is believed that the consumption of prey imparts the 'spirit' of that prey to the Kroot, which is then passed on to the Kroot's children. This is the average Kroot's understanding of their rapid evolution, with 'spirit' as a substitute for 'genetic trait'. As a part of this belief system, the Kroot believe that when a warrior dies, his spirit should be kept safe by the Kindred. They will consider it their responsibility to consume the bodies of their dead foes, along with their own fallen dead and elders. As one might expect, this custom is not viewed as an "honour" by the human warriors of the Imperium and the Kroot are considered cannibalistic savages.


The Vespid are an insectoid alien race allied to the Tau who are native to the Gas Giant, Vespid. On this world, the Vespid species live inside large floating 'islands' and stalactites. Vespid warriors, called Stingwings, form tactical units referred to as Strains. Each Strain is lead by a Strain Leader. Because the Vespid language is so complex (presumably because of their complex mouthparts) and only the Strain Leaders are given the technological apparatus required to translate their language to their Tau allies, Vespid Strains are very close knit and the Tau military relies heavily on Strain Leaders to help both sides coordinate. Stingwing Strains are highly sought after in Tau Fire Warrior Cadres because of their high level of maneuverability. They are often used by Tau commanders alongside Crisis Battlesuits or in scouting roles, backing up Tau Pathfinders. In the Tau language the Vespids are referred to as "Mal'kor," which comes from the Tau words "Mal" meaning "insect" and "kor" meaning "air".

Humans (Gue'vesa)Edit

The Tau Empire hosts a growing population of humans who were once a part of the Imperium of Man. Ranging from ideological defectors who hate the brutality and corruption of the Imperial government to captured Imperial Guardsmen and their children who have known no other life than that among the Tau, they have been fully incorporated into the Empire. While the humans from recently conquered worlds are often bitter, they do often have Tau supporters among them from the start, and the number of these Tau sympathisers only grows larger as they realise the manifest economic benefits that the advanced technology of the Tau Empire can provide. For the most part, the Gue'vesa humans are content and treated well, and are even allowed to continue the worship of the God-Emperor, though the Tau Water Caste moves subtly to discourage this religion and replace it with the Greater Good. There have also been reports that the Tau have begun to take a tougher line against some human colony worlds, sterilising their populations so that the human population will die out and leave the worlds open for full Tau colonisation. This policy was known to have been carried out following the Tau conquest of the desert mining world of Taros. Whether this represents a new Tau policy towards all humans or just a Tau desire to reserve the resources of their conquests for their own people, these actions will not be tolerated by the Imperium of Man.


Tau ground warfare is carried out almost exclusively by the Fire Caste, while the Air Caste is responsible for aerial and space combat, and providing transport between star systems for the Fire Caste. Fire Caste military forces are known as Hunter Cadres, and are similar in size and battlefield role to an Imperial Guard Company. Hunter Cadres are primarily made up of Tau from the same planetary Sept. Auxiliary forces are drawn from the alien races within the Tau Empire, and Hunter Cadres can include Kroot warriors, Vespid Stingwings, and human Gue'vesa, among other forces. The Tau prefer long-ranged combat over close melee combat where they lack an advantage over most of the other races of the galaxy (save for the Eldar) who are physically more imposing. The Tau Fire Warrior's primary weapon is the Pulse Rifle, which is used alongside the Pulse Carbine. The Pulse Rifle fires energetic particles which quickly break down and are projected as a "pulse" of superheated plasma. The Pulse Carbine, also carried by Fire Warrior teams, sacrifices range for portability, but incorporates an underslung Photon Grenade Launcher. Enemy squads hit by the Pulse Carbine also risk being disabled by Photon Grenades. The Photon Grenades not only release a powerful burst of light but also a sonic shockwave, used to disable the target and, in some cases, bowel problems in enemy troopers, much to the discomfort of those fighting the Tau. As the Tau Empire integrates more and more alien races, they use their unique abilities in their tactics. Often small alien squads will be used as bait to draw enemy fire, though it is important to note that bait squads are not considered expendable but rather dependent on the effectiveness of their cover fire. When the Tau become engaged in close melee combat, they call on their cannibalistic allies, the Kroot. The Kroot are expert jungle fighters who appear deceptively slender.

Tau SeptsEdit

Each Tau Sept (colony world) has its unique cultural identity but remains wholly integrated within the greater Tau culture. This cultural identity seems to mainly derive from which Tau caste is more numerous and influential in the given Sept. Currently there are over twenty fully-developed Tau Septs within the Tau Empire. Each Tau Sept has its own Sept badge.


  • T'au, the homeworld of the Tau race. T'au is the capital world and spiritual, political, cultural, and administrative centre of the Tau Empire. Its citizens are considered especially learned and wise byother Tau.
  • Pech, homeworld of the Kroot.
  • Vespid, jungle homeworld of the Vespid.

First Sphere Expansion SeptsEdit

The First Sphere Expansion of the Tau Empire began shortly after their species first achieved spaceflight capability. The Tau homeworld and the First Sphere colonies are of major economic and political importance to the Tau and form the hub of the Tau Empire.

  • Tau'n, the Tau's first offworld colony, Tau from this world are considered to be pioneers.
  • D'yanoi, having been isolated for a time from the Tau Empire, its inhabitants are considered somewhat rustic and backwards.
  • Bork'an, a Tau centre of learning and academia.
  • Dal'yth, a cosmopolitan and trader-friendly Sept.
  • Fal'shia, a centre of technological development, Tau from Fal'shia are considered great problem solvers.
  • Vior'la, a major military centre of the Tau Empire, Vior'la's Fire Warriors are considered especially aggressive and skilled.
  • Sa'cea, another Tau military centre, Sa'cea produces a very high proportion of exceptionally-disciplined and honourable Fire Warriors.

Second Sphere Expansion SeptsEdit

The Second Sphere Expansion of the Tau Empire began shortly after the end of the Damocles Crusade in 742.M41 that had been launched by the Imperium of Man to keep the Tau's expansion into Imperial-controlled space in check. Of note are the settlement activities of the Fire Caste's Commander Farsight during this period.

  • Au'taal is a beautiful Tau Sept, whose citizens are considered easygoing and often lazy by other Tau.
  • N'dras was abandoned by the Tau for unclear reasons. Its remaining inhabitants are regarded as unstrustworthy, quick-tempered, and of a brooding countance.
  • Ke'lshan has suffered several raids by other alien races. Tau from this Sept have grown mistrustful, solemn, taciturn, unfriendly and sometimes openly hostile to alien races. Ke'lshan was invaded by the Tyranid of Hive Fleet Gorgon and its citizens played an essential role in stopping it.
  • Elsy'eir is known for its poetry and artwork. Its citizens are considered intellectuals and well-respected for their creativeness by other Tau. The Earth Caste is dominant on Elsy'eir.
  • Tash'var was raided several times by Orks and human pirates. Its people are regarded as tenacious, hardy, practical and courageous.
  • Vash'ya seems to be primarily inhabited by members of the Air Caste and is a major orbital shipyard for the Tau Navy.
  • T'olku is a Tau Sept known for the unusual skill of its Ethereal diplomats.

Third Sphere Expansion SeptsEdit

The Third Sphere Expansion was begun by the Tau Empire on 977.997.M41 on the word of Aun'va. The Fire Caste's Commander Shadowsun was placed in command of the expansion, and has secured at least two new Septs for the Tau Empire to date. During the Zeist Campaign of 999.M41, Imperial Space Marine forces counterattacked against the expanding Third Sphere, drawing the Third Sphere Expansion to a halt. However, during the course of the Third Sphere Expansion, the Tau Empire had grown to 133% of its size prior to 997.M41, largely as a result of the Imperium of Man's distraction during the 13th Black Crusade and its aftermath in 999.M41. Two recognized Tau Septs settled during the Third Sphere Expansion include:

  • Ksi'm'yen, the colonists of this Tau Sept seem to be associated with luck, subtlety and opportunistic subterfuge.
  • Fi'rios, a Sept whose Air and Earth Caste pioneers are recognized for a tenacious refusal to accept defeat, tempered by a stoic acceptance of the price all must pay in the furtherance of the Greater Good.

Smaller Tau worldsEdit

Besides the populous, fully-developed Tau Septs, there are also more sparsely populated Tau colonies. Only a few names of such Tau colonies are known to the Imperium:

  • Me'lek
  • Es'Tau, settled during the Second Expansion.
  • T'ros, recently settled during the Third Expansion.
  • Sha'draig, invaded by the tyranids' Hive Fleet Gorgon in 900.M41. The Tyranids of Hive Fleet Gorgon were eventually driven off the world, but not before it was almost completely consumed by Ripper swarms.
  • Ka'mais - invaded by Tyranid Hive Fleet Gorgon in 902.M41. A hidden Necron fleet emerged from Ka'kais' dead moon and destroyed the outnumbered Tyranid bioships, but then continued to land on Ka'mais and harvest the planet's population for its C'tan masters.
  • Ho'sarn - This Tau colony was evacuated in 902.M41 as Hive Fleet Gorgon approached. But the evacuation fleet was ambushed by the Hive Fleet's bioships and completely slaughtered.

Non-Tau WorldsEdit

During the First phase expansion the homeworlds and colonies of the Kroot and of the Vespid were also incoporated into the Tau empire. Notice that these star systems are not considered septs

  • Pech, homeworld of the Kroot. There are eight star systems in the Tau Empire inhabited by the Kroot (including Pech). The Imperium knows only the name of the planet Krath, where the Tau first encountered the Kroot.
  • Vespid, tropical homeworld of the Vespid insectoids.
  • Roksh XVI - site of a secret Tau listening post, the planet was part of the Roksh System that was home to the Rokshashi Wealthweb merchant guild before the entire star system was consumed by the Tyranid Hive Fleet Gorgon in 689.902.M41.

In addition there an unknown number of former Imperial worlds within the Tau Empire, some or all of which might still have a human population (see also Gue'vesa above).

Artefact worldsEdit

Three Artefact worlds are located within the borders of the Tau Empire. As the name indicates, ancient artefacts of unknown origin have been discovered on these planets. It is not known if these worlds have Tau colonies at all.

  • Arthas Moloch, a dead world where Commander Farsight found the Dawn Blade.
  • Q-15
  • Landfall

Farsight EnclavesEdit

The only known breakaway faction of the Tau Empire is the alliance of Tau colony worlds called the Farsight Enclaves that were placed in the Damocles Gulf against the orders of the Tau Ethereals. These worlds are led by the Fire Caste's Commander Farsight and were conquered from the Imperium during the Tau Empire's Second Sphere Expansion. These enclaves have less regard for (or a non-standard interpretation of) the Tau'va, the philosophy of the Greater Good. Most of their names are currently unknown.

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