Mirdesh Confederacy

The Confederacy of United Nations of the Universe, commonly known as the Mirdesh Confederacy, is a galactic supranational union located in the far west of the known Galaxy. It encompasses over 350 worlds and has a population of around 160 billion. It is made up of 173 constituencies with 22 representing individual species. Often considered a nation, it is the largest by population, number of worlds, number of systems and GDP. Whilst heavily centralised for a supranational union, the Confederacy remains decentralised relative to most other galactic nations. Nearly all matters other than foreign affairs are made by individual constituencies. The capital is located on Pelanna, in the Zurimiel system. Unlike most other nations, the Confederacy has no proper "core" sector where most population and economic centers lie. Instead, the population is spread out in around a dozen regions which are heavily populated, each one of which encompasses around ten worlds. 
The Mirdesh Federation is the oldest galactic nation to still exist. It was formed near the end of the 18th century AD. At the time, it was already spread out across its native system. It appeared as a successor to the Mirdash-Zurkari Federation. These had been two sapient species which evolved nearly completely separately on the two supercontinents of their homeworld of Pelanna. The two species had evolved to become peaceful communal societies, and rapidly found common ground. Within a century of first contact, a planetwide government had been formed. Whilst at a similar technological level as humanity in the early 1400s, by the end of the 17th century the Mirdash and Zurkari had entered their space age. In the mid 1700s, they made first contact with the Meldari, who evolved on another planet of their home system. Whilst not as peaceful as the Mirdash and Zurkari, the Meldari soon found themselves extensively trading and communicating with the Mirdash-Zurkari, who at the time were techologically much superior. By the end of the 18th century the Meldari had been technologically uplifted and fully integrated into the newly formed Mirdesh Confederacy. 
The Mirdesh would continue their space expansion, discovering the warp drive in 1823. They would peacefully integrate over 15 different species, and would force 6 other, more bellicose, species to join. Due to this immense headstart compared to the Ur-Han, Surben or Terrans, their population is a few times larger. However the plethora of species present within their borders has caused numerous uprisings and other forms of civil unrest over the centuries, with the current most prominent being the Teljum War. 
The Confederacy is heavily decentralised and many institutions are left to individual constituencies, for instance currency, defence and economic policy. Although all constituencies are nominally equal, Mirdesh politics are dominated by its three founding species, which have coalesced into an informal alliance known as the Triad. They represent over four fifths of the population and over a quarter of all constituencies. This heavily decentralised system ultimately results in heavy dissatisfaction by both regionalist groups seeking more autonomy and centralists which aim to concentrate more power in the Confederacy. Additionally, the technological disparities between constituencies are vast. This has been exploited by external influences, most notably the Terran Federal Republic and its corporations which sell technologies to underdeveloped constituencies. The ineffectiveness of the Mirdesh system has made it both stagnant relative to the other major galactic powers and rendered it unable to reform itself. 
The name Mirdesh is derived from the name of the founding species of the Confederacy, the Mirdash. However the Confederacy recognises no species as "leading", and instead considers itself a collection of multiple equal species.