The Tau rule a small interstellar empire on the very fringe of Imperium space. They are a relatively new power on the galactic scene. The Tau dream of uniting the races of the galaxy under their benevolent rule (by force if necessary). The Tau already rule a number of client races, including some annexed human worlds.
The Tau home planet, was discovered in 789.M35 by the Adeptus Mechanicus Explorator Fleet ship Lands' Vision Adeptus Mechanicus records indicate that at that time, the Tau species had mastered the use of simple tools and weapons, as well as fire. Before the planet could be cleansed and colonized by the Imperium, however, a violent Warp-storm erupted around the planet. This continued for 6,000 years, making the Tau's homeworld utterly inaccessible.
It was not until the Damocles Crusade that the Imperium again contacted the Tau. The Imperium found the primitive Tau had advanced considerably. In six thousand years, the Tau had advanced from spears and fire to colonizing planets and Pulse Rifles.
The Tau are oriented towards ranged combat and generally die quickly in close quarters. They have some of the most powerful ranged weaponry in the game in terms of both range and stopping power, with their railgun being the most powerful of all. The Tau do not have any psykers or units that specialize in countering psykers, which makes them somewhat more vulnerable to psychic attacks. All Tau vehicles are classified as flyers, skimmers, or jet pack infantry, meaning they can all move swiftly over difficult terrain. The Tau are the only army in the game that routinely incorporates aliens. Kroot warriors provide melee support, while the insectoid Vespids serve as jump infantry. 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 so-called Sphere Expansions. 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 colonised, conquered, or sometimes peacefully persuaded to accept the Greater Good through diplomacy and a manifest demonstration of the benefits provided by advanced Tau technology. The introduction of the Ethereals to Tau society led to the creation of a rigid Caste System, with each caste taking on the name of an element that is close to them. Thus, the warriors of the Tau Empire became known as the Fire (Shas) Caste, due to their fiery temper. The artisans and scientists became known as the Earth (Fio) Caste, being the most pragmatic of the Tau. The diplomats and administrators became known as the Water (Por) Caste, as water flows through all life, uniting it. Lastly, the Tau messengers and spies became known as the Air (Kor) Caste, traversing the land on top of gusts of wind. With the invention of aircraft, and later spacecraft, the Air Caste would become the pilots of the Tau Navy. The Tau are the most open and tolerant of the races in the galaxy, which means that they prefer not to destroy all other races on sight and are nowhere near as xenophobic as the Imperium. They are appreciative of the ways of the humans, Eldar, and other sentient races, but hold their own values as superior above all others. Their tolerance also extends to themselves, as the Tau recognize even lowly Fio'la workers as being as important to the operation and well-being of the Empire as Shas'vre Battlesuit leaders or even the highest Aun'o. The Tau evolved as hunter-gatherers in the arid plains and desert environments of their homeworld, T'au, though they eventually spread to all ecological regions of the planet. As a result, they have tough, leathery blue-grey skin, which exudes no moisture. With an average height of 5'5", they have a humanoid body plan, though unlike humans they possess digitigrade legs which end in cloven hooves. The Tau have flat, nose-less faces, with their olfactory organs located inside of their mouths to preserve moisture. On the battlefield, the Tau typically wear all-concealing battlesuits which give them an even more alien or robotic appearance, but a Tau soldier that takes his helmet off for a closer look will reveal that their cranial arrangement isn't that much different from a human's (compared to say, a Tyranid; they don't look as similar to humans as the Eldar). The different Tau castes have slightly different body proportions between themselves.
The Greater Good, or "Tau'va," is the central philosophy that unites all Tau. It teaches that every sentient being is equal and plays an important part in Tau society. It tells its adherents to put away petty squabbles and unnecessary things to unite for the greater good of the rest of the race. The Tau have no desire to destroy another intelligent species' religion or culture - though it may not mean that the Tau respect the right to live. However, while many embrace this ideology (even some Imperium worlds have willingly joined the Tau Empire) other races fiercely resist adhering to the Greater Good to pursue their own freedoms, much to the dismay of the Tau, who see these desires as selfish and unenlightened. The Tau castes are: Fire-caste - Warriors, both ground soldiers and vehicle drivers. The caste most likely to be encountered up-close on the battlefield. Skilled hunters and fighters, they are larger and stronger than other castes (some of the other castes are taller, but do not have proportionately as much muscle mass). Air-caste (also known as the invisible caste) - Pilots, both in the merchant fleet and staffing the military starships of the Tau Navy, commanded by Air-caste admirals. The Air-caste have been living and working in microgravity for so many generations that they have become exceedingly tall and slender, with unusually long and skinny limbs. They possess heightened depth-perception, high-G tolerance, and perception of 3D environments. Earth-caste - Builders, farmers, miners, engineers, and scientists. The Earth-cast forms the backbone of Tau infrastructure and population. They are short and stocky, with a generally stoic outlook on life, diligently performing their work. Their labor is respected, and considered no less valuable to the overall effort of the "Greater Good" than the functions of the other castes. Water-caste - Merchants, bureaucrats, mid-level administrators, diplomats, ambassadors and scientists. The Water-caste is the group of Tau most likely to be encountered in formal diplomatic missions sent to other races. They are somewhat taller than other Tau, though not as tall and slender as the Air-caste. Ethereals (sometimes referred to as the "Celestial-caste") - Leaders, both spiritually and politically. Relatively few in number, though generally they seem to be about as tall as the Fire Caste, though not quite as strong physically. All Tau have an irresistible compulsion to obey the word of an Ethereal. It is not known whether this power is psychic or pheromonal. Thus, there is very little politicking among the Tau. About Member races The Tau are the only faction that willingly accept other races into their ranks. Typically, the races are extended a hand from the Water Caste first, and if they still pose a problem or otherwise refuse to be reasoned with, the Fire Warriors are sent in. It should be noted that tau usually are not in haste of annexing the world, and if the aliens don't want to join right now but aren't immediately hostile and open to trade, Water Caste would slowly but surely convert them into a Greater Good to the point that one day they themselves would ask to join the Empire. The species, when annexed or conquered, are usually allowed to keep their planet, but must answer to the authority of the local Ethereal and possibly the local Shas'o. Most of them are fluff, but it would get a little ridiculous if you could purport to play a 'single' 40k race that included, like, twelve different races. So join The Tau FOR THE GREATER GOOD. Signed Moddlord1