Spheres of Expansion

The Spheres in general, as shown in general...in a sphere map.

The Spheres of Expansion is the term for the five major waves of Tau colonization and conquest that effectively exist as the slowly growing "borders" of their empire, characterized by the many Septs and satellite colonies and resource gathering operations that grew out of centuries of exploration, colonization, conquest, hard-fought wars, and ultimately further expansion once the resources were there to move on, in a glacially paced but never-ending cycle of the Tau Empire attempting to get getting bigger and more relevant to the Galaxy at large.

Origins

With the Tau empire's founding, the obvious thing any empire does is look around at all the things that it could have and decide to make it theirs, in this case baked into the philosophy of every caste, where all castes inevitably see the stars as yet another place for the Greater Good to take root and build homes with. Though unlike Imperial expansions, that effectively dumped a mass of humans on planets only nominally agreeable to life and expect them to make it work, Spheres only ever come about when ordered by the Ethereals, and only starts to take hold when a world has been completely scanned, vetted, colonized, and then utterly dominated by the Tau and have become a stable settlement. The first world to do so becomes a Sept. While yes, the Tau take over star systems at a snail's pace, they do it in a much more stable fashion than their neighbors, with only a few central hubs where all the resources go and are sent from, and allows for the Tau military to iron out the kinks of whatever current problem happens to be bothering them this week, rebuild from the ordeal, and eventually move on when the next Sphere is declared.

While the Tau only control a relative handful of worlds, the work they had to put in to get each of the five spheres that exist put together and fully functional is considerable, especially in a galaxy that cares little for their optimism, and they will defend the borders of each sphere with pulse-dakka the likes of which would melt planets.

The First Sphere - The Greater Good's first real test

The very first and greatest expansion of the Tau, where all the biggest Septs that you may be marginally aware of come from, and the first sign that the Tau were on their way to becoming bigger players on the galactic stage. The seeds were planted as the lead planet of T'au began to experience overcrowding as the technology they had repurposed and built exploded out, and eventually the Ethereals at the time decided it was time that this Empire made their way into the stars, and called for the Earth and Air caste to start building colonization vessels, and turn their messengers into pilots. The progress was slow, as the Tau scanned their local star system and set up orbital stations, scouting probes, and extensive testing to ensure every planet they wanted to go visit wasn't going to rip them apart like their homeworld used to. It took well over a millennia to complete, but by the end, they had millions of their species across eight, tightly compacted worlds, all interconnected and working towards building the rest of the empire.

Of course, no gravy train lasts forever, and eventually the first Sphere's expansion came to an end due to two things: Lack of FTL travel...and Orks. Lots of Orks. The Tau, new to this whole "the entire Galaxy is trying to kill you" thing, took a considerable toll from their first interactions with the Green tide, and spent untold resources keeping their rowdy green neighbors from plundering every pulse rifle they could ever want. Further, while they had plenty of increasingly powerful and high tech shit to keep the bad alien at bay, their ability to traverse the stars were tapped, and even as the Ethereals tried pushing harder and harder, the reality that they faced was that they'd gone from a world bursting with blue communists to an empire stretched thinner than excuses for the plot armor their race had. Things looked like they were going to be stuck in their own stellar neighborhood for the forseeable future...right up until they met some Kroots getting attacked by Orks from orbit. They naturally showed up and pew-pew-pew'd their assailants, and met their new beakie friends. They liked the Kroots for their absolutely absurd numbers and fierceness in combat, and the Kroots liked hanging out with the Blue guys who could bullseye predators from a kilometer off. They decided to become best buds, and the Tau and Kroots helped kick the Orks out of each other's star systems (for the most part), and rope them off into fighting each other when they couldn't. Things began to even out for the Tau, as their discipline grew, their numbers grew, and the empire was finally beginning to look like an empire. A minuscule one, but an empire nonetheless.

And then the Fal'shia Sept suddenly had a massive breakthrough. And it was off to the races again.

Second Sphere - Cooking with gas, and the burns that result

It cannot be overstated how important the ZFR drive is to the Tau: without it, they'd still be struggling to hold eight worlds, occasionally backed up by Kroot. But once the ZFR drive was tested and proven, the Etherials decided that time was once again to go and spread the Greater Good to the universe, and this was by far their most aggressive expansion, nearly doubling up the number of Septs founded from the first, and to this day remains their most successful sphere. A good portion of that expansion came from Commander Puretide, who began his legend during this crucial expansion, striking fear and concern into the heart of all orks everywhere by doing something Orks couldn't process: he made combat not fun. And nothing was worse than a fight that wasn't fun. These incredible tactical victories against such a foe were so great that the Tau were finally able to cross the Damocles Gulf for the first time, something that had eluded them for centuries.

Of course, it wasn't all sunshine and daisies; they were able to found just as many septs as they were because they continued to follow the same path of "closest cluster of stars and planets seems safest to go to", and were still running headlong into multitudes of Ork invasions. It was also here on the other side of the Damocles Gulf that the Tau got to meet the biggest power in the Galaxy: The Imperium of Man, and humanity. Initially, they had run into only the very isolated and not all that loyal worlds just outside the gulf, who had been cut off by warp storms and Eldar Corsairs, and at that point were willing to take help from whoever could give it, meaning eventually the Tau ended up colonizing those worlds fairly quickly and painlessly, assuming that the Humans would be a fun new friend to bring the Greater Good.

And then the warp storms ended. And the Imperium came back to see what had happened and were not fucking pleased by any of it.

So yeah. The Second Sphere's expansion period kinda ends in a hard snap after that whole debacle, and to this day the T'au borders rare if ever expand too far beyond the Damocles Gulf. And just when they started to consolidate resources and make ready for the next phase of their development, they got an uninvited visit from Hive Fleet Kraken and it's many splinter fleets. And the Orks came back in force, now fully interested in giving the Tau a taste of what REAL fun combat is supposed to be like, and were only finally beaten back after losses beyond measure by unfreezing one of Puretide's greatest students and giving them near total control of the entire combined forces of the empire, and a thorough scrubbing thereafter.

Needless to say, it was a couple centuries of rebulding to go before the next Sphere got going.

Third Sphere - Sneaking back in

Having well-learned that going after the Neighbors without a plan was a BAD FUCKING IDEA under any circumstances, having still kept a good portion of the Septs they'd set up together, and now a fully realized understanding of what their neighbors were capable of and the tactics necessary to defeat them, The T'au decided it was once again time to go stretch their behooved legs across the galaxy, and this time, they'd come prepared. Long held zones of exclusion were entered by fleet after fleet, purging rebels, orcs, and Hrud wherever they could in order to set up new Septs. Further, their decision to use Water Caste ambassadors to undermine imperial authority on the otherside of the Damocles Gulf paid dividends in getting the humans on their side of the Gulf to give up and annex themselves without much fighting, ensuring that finally, they had a stranglehold on it.

Emboldened, Shadowsun dove deep into the imperium, using strategies and counterstrategies that seriously caught the worlds of the Emperor off-guard. And it all came to a head at Mu'Gulath Bay, where the Tau were dropped into the Imperium's style of Warfare: Bitter, grind-y, all out warfare they simply could not comprehend. Finally, the Assassinorum got involved and headshot'd a lot of Tau leadership, and all seemed lost right up until a certain Pariah and his goons showed up and won the day, but not the war. The Humans blew Mu'Gulath bay sky-high, and set the entire Damocles Gulf on fire just to make sure this wouldn't happen again. It was those actions that brought the third sphere to a screeching halt, but had ensured that the edges of the Damocles Gulf would remain at least partly T'au-controlled for the time being.

Fourth Sphere - Mission Failed

The Fourth Sphere was a colossal and utter failure mostly brought about by terrible luck...and sheer fucking idiocy.

See, since the Damocles Rift was now on super-fire, going FTL through it was next to impossible, and had effectively put the entire Tau Empire into a playpen that the Imperium wouldn't have to deal with for another x-thousand years. Or, that was the idea anyway. Had they bothered to clean up any of the ships that'd been perforated by Railguns, they might've been able to stop what happened next, as the Tau reverse engineered parts of a Warp Drive, and fitted that into their new Armada, with the hope that they'd be able to cut through the Gulf again and get back to spreading the word of the Greater Good. And to do that, they set up their armadas right on Numenar Point, a place close to the Gulf, and had a big long broadcast about how much fun this was all gonna be and all the new places that were gonna be in on the greater good, and at the end of the speech, every single one of those experimental, not entirely well understood warp drives fired up at once just as the Great Rift opened, and every single one of those warp drives helped create a sudden, violent hole in reality that ate the entire fleet in front of an audience of billions, and while the Etherials worked overtime to ensure nobody was truly aware of what was going on, they decided that something like that ever happening again would be a deathblow to their credibility, and basically disassembled any further prototypes.

But then there was the matter of that hole, which had roughly healed into a wormhole known only as the Startide Nexus, from which the Etherials were very concerned if anything at all would come out of there. After all, they were now fighting against some warpfuckery that was dragging their Gue'Vesa and their non-Tau auxiliaries into total madness that they now had to deal with, as well as all the other things that usually came looking for a piece of the Tau, and they declared that the space around the Nexus should be well-defended, creating an enormous interconnected ring of fortress-space stations that basically had more guns than breathable spaces trained on it, just in case. It was said only T'au had more fortifications at the end of construction.

And then something unusual happened. A probe came out of the Nexus. A Tau probe.

From the Fourth Sphere Expedition Fleets. They'd survived after all.

Fifth Sphere - Deep Space N'Ine

This is the current Sphere of Influence attempting to gain a foothold in M42. It took months of cajoling by the Fire Caste to attempt to cross the Nexus, but after a second probe was sent, this time with actual information from a major commander, the Ethereals gave their blessing to allow an expeditionary fleet to cross into the Nexus, and when they did, they found that they had ended up in the Chalnanth expanse, a part of the Ghoul Stars far away from the Empire. Naturally, they enquired to the survivors as to what had happened, and the best answer they got was that they got sucked into the Warp, and many of the Non-Tau auxiliaries perished in the process, if they were lucky. Of course, that didn't mean the Tau who made it to the other side of the rift hadn't been affected either; they seemed cold and distant, scarred by their sudden escape from the Immaterium, and very defensive around the Auxiliaries that the 5th Sphere brought with them, and basically had to be held away from any of them.

Of course, that didn't mean the Fifth Sphere had to stop. They had all those Fire Warriors and Battlesuits and goddamnit they were gonna have to use them if they wanted to make it in this absolutely terrifying new expanse of space. Using the chaos created by the Great Rift, they were able to once again convince dozens of worlds to join up with the empire, but soon had to basically haul almost the entire surviving part of the Fourth Sphere Expansion back to T'au for brainwashing, shaming, and reconditioning, as they were going around doing un-Taulike things like killing prisoners or taking pleasure in shooting non-Tau. The Etherials, naturally, recognized that while this Nexus was a massive boon, it would pretty easily be a curse if left carelessly undefended, as it empties out right in the Empire's backyard, and have taken great steps to fortify the new Septs that came about from this expansion, as well as the Nexus' end point with just as much orbital dakka as the beginning point, hopefully ready for what comes next.

And then the Death Guard showed up.