T'au Empire - The Mont'au and the Coming of the Ethereals: The exact date of the founding of the T'au Empire in the Imperial Calendar is unclear. However the way in which the T'au 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 discovered the T'au homeworld of T'au and determined that its population of intelligent xenos were a primitive people at the Stone Age level of development, having only just mastered fire. Since then, the T'au have developed very rapidly into a space-faring species.Earlier in their history, during a period known as the Mont'au, the T'au were a culture built upon warring tribes. During this time, the T'au'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 T'au warriors from the plains. Though negotiation had been attempted, the fierce plains warriors would settle for nothing less than the annihilation of the city of Fio'taun.For five long T'au years the inhabitants held off the savage assaults with their thick walls and plentiful cannons. However, disease and starvation began to take their toll. As the tide of the siege turned, two mysterious T'au appeared. One made his way into the camp of the plains T'au, exuding a quiet authority that no T'au was able to resist. Soon, the leader of the plains warriors was persuaded to parley with the settled T'au of Fio'taun. Similarly, the other mysterious T'au made his way deep into the fortress. Within a few short hours, the gates stood wide open, and T'au of both sides stood ready to talk.The Ethereals spoke of the importance of peace and understanding between all T'au. They described a Greater Good that each T'au 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 T'au united, they were able to rapidly develop their civilisation's technology, ultimately attaining spacefaring capabilities.The T'au Empire soon expanded its borders through a series of so-called "Sphere Expansions." The T'au Empire has gone through five main phases of expansion as of the Era Indomitus in the 41st Millennium. These phases are marked by T'au military campaigns during which new worlds and star systems are colonised, conquered, or sometimes peacefully persuaded to accept the Greater Good through diplomacy and a manifest demonstration of the benefits provided by advanced T'au technology.Apart from the star systems directly colonised and exploited by the T'au, which are known as "septs," the T'au 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 Leagues of Votann Prospect called the Demiurg by the T'au are full members of the empire, allies, or mere trading partners. The T'au 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 T'au are the Farsight Enclaves, founded beyond the Damocles Gulf by the T'au Commander Farsight against the orders of the Ethereals. More recently, some worlds and star systems of the Imperium have been conquered by the forces of the T'au, while a handful have seceded from the Imperium outright and pledged their allegiance to the T'au Empire and the Greater Good.