I had some differing lore in my RP, with regard to the size of the Alliance. Actually, I had some switches and forks where I had the Tyandirr as the main faction (they even invaded the VC homeworlds). That is not canon and this post sort of describes the relationship between the Tyandirr Imperium's Third Empire, and the other races; namely the Senlani and the Volcyon. (I typed that today). The first bit is from a while back.
As of now, it is the "Five Trade Alliance"; without wanting to add a spoiler, (lol) I am planning to unite the VC and UTN "forks" of my universe together, as they in different arms of the Galaxy, and eventually Humanity will join the Alliance and form the "Six Trade Alliance" and all the alien races would maybe unite against a common enemy; the Radacri.
It's interesting because I had the Radacri as one of the Alliance races at first (but to unite the universes, I will make them the common antagonist). This will be pretty cool. :D
By the way, this is WIP where it is stated and subject to amendments as I finalise the lore.
Update (25/04/2020) this is now Canon, before Humanity was included with the formation of the U.A.S in 4299 A.D
Summary – Races of the Five Trade Alliance
The Five Trade Alliance is made up of Five races, including the Volcyon.
A highly advanced race hailing from the Great Circle, in Sagittarius Cluster. They trade in advanced technologies, but usually keep to themselves. Often considered some of the best clients of the Corporate Clans, the Aurc are highly regarded for their premium tech and often supply ship systems and shielding technology to the VC Military.
The Sector Rim Federation
A race hailing from the Sector Rim; on the verge of Sagittarius. The client species of the Republic are the Senlani; a humanoid species that are renown for their cultural diversity and rich traditions. Biologically similar to humans, the Senlani Federation is often considered the cultural hub of the Alliance. Diverse peoples, exotic foods and skilled craftsmen all hail from Senlani space. They are respected for their engineering skills.
An aggressive, militant species hailing from the Taran Nebula in the Deep Red. The latest species to join the Trade Alliance, the Tyandirr started a war with the Conglomerate. Eventually gaining trust and being accepted into the Alliance ,the Tyandirr are expert warriors. Crafting the finest weapons and military equipment in the Alliance. Their aggressive nature often calls for VC involvement in mediating with the other races, but their export of military gear is considered invaluable to the Conglomerate's Navy. The Tyandirr also provide ground and shock troops, and marines for Conglomerate vessels.
A peace-loving, highly religious and advanced species, hailing from the Orius Cluster. The furthest away from the Alliance, the Zel'Kror utilise advanced Gate Technology to trade with the other races. Very little is known about the Zel'Kror, as they, like the Aurc, keep to themselves and their isolated location adds to the mystery. They primarily buy raw materials and ores from the Alliance, but have also provided Gate Technology to the Conglomerate, which allowed faster travel between sectors.
Uneasy 'peace': The Tyandirr Third Empire and the Conglomerate
The situation between the Five Trade Alliance's two most powerful species; the Tyandirr Imperium's Third Empire, and the host species, the Volcyon Conglomerate, is an uneasy one at best, almost hostile at worst.
The Volcyon know the Tyandirr are by far the most powerful race in the Alliance, in terms of military strength and aggression. A war between the Third Empire and the other races would be catastrophic, and result in unimaginable losses in profit to the Conglomerate. While the VC's military is extremely potent, even it would not be able to sustain a war with the Third Empire. The Volcyon know this, but seeking profit always, they are master manipulators of their honour-craving allies.
The VC government had created a sense to the Leading Clans of the Empire, that the Tyandirr were in a position of power in the Alliance. In a sense, that other races (especially the Sector Rim's Senlani, of which are almost hostile to the Tyandirr and vice-versa), are subordinate to the Empire, an attitude which keeps the Tyandirr happy. While the facade continues, the VC know that they are the true influencers, and that suits them just fine.
The Volcyon often exploit the "Shadow Council" of the Tyandirr; a circle of revered female councilors not often known, that influences major decisions within the Empire's power structure. It is known to the Conglomerate, that these Females are likely behind almost all major decisions; and that while the out-lookign face of the Empire is male-dominated patriarchy, it is in fact the less aggressive, more diplomatic Females that keep them in check. These Female councilors have enormous sway with the Leading Clan and the Emperor himself, and they are more than happy to work with the Volcyon on important matters.
Many times the Volcyon government has manipulated (the term "teased" is more appropriate...) the Tyandirr Clans to do their dirty work, especially when such "work" is met with opposition from other members of the Five Trade Alliance. The Senlani, mainly, are highly moral species very similar to humnity. One such objection took place in the example I will give now:
On the fringe of explored space in the Deep Red, Volcyon Trade Fleet scouts discovered a new world named Vecrah-III (it was initially claimed by the Conglomerate and follows their naming scheme), and upon surveying this planet, they found enormous deposits of a rare resource that is prized amongst the Volcyon, simply known as "Vol", this element is similar in compositition to the human-discovered "Polaryte"; and is a unique element in the Galaxy. The rarity of this element, and the use in critical manufacturing technologies for the Conglomerate's Industrial Complex, places an absolutely enormous value on it. More so than any other resource.
The Trade Fleet, of course, petitioned the Trade Council to allow a full-planetary strip-mining operation. The Council, in anticipation of the huge influx of profit, almost authorised the operation - which would essentially crack-mine the crust of the world, destroying its surface -, except for the objection of the Senlani, who's own scouts had discovered something else on the surface of Vecrah-III.
An intelligent alien civilisation had spread across its surface, they were primitive, likely in their 'Middle-ages' in comparison to human history. In that Kingdoms and primitive buildings and cities, their weaponry culminated in bladed weapons similar to swords. The unnamed species was many thousands of years behind achieving space-flight or similar. To the Volcyon, this was a minor concern, and as their "Shadow Corporations" ruled; this primitive race was worth less than the potential trillions of Crels that would be profited from the destruction of their world.
The Senlani, whose scouts also found Vecrah-III, objected to the Trade Council and petitioned that the world be given protected status to preserve the race and allow them to develop. Truly a moral decision in a morally-grey universe. To the Volcyon, just going forward with the crack-mining would result in low support from the Senlani, and a reduction in profits as they withdraw trading assets from the Alliance. The Volcyon are master tradesmen; they know a happy Alliance, is a profitable one. Unwilling to act upon the world against the wishes of the Sector Rim Federation, the Volcyon Trade Council instead turned its attention to the Tyandirr, who's brutal conquest of the outlying sectors already claimed many lesser developed races.
The Tyandirr are likely somewhat aware of the manipulation that went on, regarding Vecrah-III, but their culture of honour and the internal respect hierarchy of the Leading Clan left the emperor no choice, and besides, the Empire would jump at the chance of a new world to conquer. The Volcyon Conglomerate secretly sowed distrust within the ranks of the Tyandirr's leading Clan, the seeds of which grew into challenges of power, and to the Tyandirr; this is unacceptable. The Volcyon slipped the location of the new world to the Empire, and knowing that a new Conquest was needed to cement its dominance, the Leading Clan would wipe out the world as they had done so many times before.
The result was the brutal conquest of Vecrah-III, and the exitinction of the unnamed species. The Tyandirr brutally hunted down and slaughtered every single male, female and young of the race in a 3-cycle conquest that resulted in 100 million aliens being slaughted, eaten and wiped out by Tyandirr Imperium's Elite Shock Troops. The Conequest was complete, the Leading Clan proved once more that it is worthy, and the Volcyon; knowing that the Senlani would not question the act of the Empire; had a clean slate upon which to reap their rewards.
The Tyandirr Third Empire and the Sector Rim Federation
The Senlani; a humanoid species from the Sector Rim, making up the main species of the SRF; named for that Sector, were almost wiped out by the Tyandirr Third Empire's initial conquest of the Deep Red, only the intervention of the Volcyon Conglomerate saved them as a species from near extinction, enslavement or submission into one of the many, brutally oppressed thrall races of the Empire. The Senlani military is powerful, but small. They are fully aware they cannot win any kind of armed conflict with the Deep Red's most powerful military force; the Tyandirr Imperium.
Through mediation on the Trade Council, they live in an uneasy co-existence with the Tyandirr in the Five Trade Alliance, the Empire simply tolerates their existence at best, and almost acts upon its aggression at worst.