Ysi is located in the Zaonur system in the Large Magellanic Cloud and orbits it as the first planet. It is the only planet in the system where life developed. It is a fairly prosperous world today, harboring 2 quadrillion souls. It has become a mini ecumenopolis of sorts, a center of trade and power in the local region. It's current prosperity hides uglier scars from violent days long since past.
The world is the homeworld of the Ysau, and the former capital of the Interstellar Systems of Ysau. From 22,006 to 23,404 the Ysau were engaged in a war with the Confederacy of Borealis that ultimately destroyed the Interstellar Systems and caused trillions of casualties. This First Magellanic War devastated the species and the planet, taking centuries to recover and longer to regain trust both in and from the wider Confederacy.
Ysi has no surface water- the planet is too hot for water to stay in a liquid state naturally. The planet is one continuous landmass, and that landmass is largely dominated by three biomes, two of which are natural. There are vast cities covering much of the planet's surface, mostly established atop the deserts that still dominate some swathes of the planet. The only regions mostly untouched on Ysi are the forests. The forests of Ysi hold special meaning to the Ysau. The Ysau evolved in these alien forests, among the giant trees that were freezing to the touch so as to obtain water from the air, alongside the other animals scavenging for water and food, and in spite of the apex predators that would hunt the smaller species to suck the liquid from their bodies.
These forests are truly sprawling. Several, on a planet about 1/10th the surface area of Earth, are greater than a million square kilometers, and of those two are larger than two million. The alien trees have jet black protrusions to catch and cool water in the atmosphere to convert into usable liquid. Some Ysau choose to live in much smaller cities deep in the forests, even if only temporarily, to get in touch with their ancestry and home.
The cities that cover the planet are no less massive. There are pockets of desert, and desert rings many cities, but the percentage of the surface that is manufactured is significantly higher than the percentage that remains natural. These cities mostly take after traditional Ysi architecture, Utilitarian and ingenious. Most buildings are built for function over form, but the Ysi make the most of every inch and incorporate features into buildings that can be used for two, three, four, or more applications. A Ysi room can change entirely based on the situation it's needed for, and indeed many Ysi live in single rooms with all the accommodations of a full sized home.
The culture of Ysi is naturally influenced by that of the Ysau, but aspects of the Confederacy have bled into that culture over time. For example, Ysau is still a language taught in schools, but it's an optional class, with most Ysau speaking Common. Nevertheless, the simultaneously utilitarian, mystical, and idealistic Ysau culture is still very visible here, with the isolated and more stylized forest cities contrasting the larger sprawls, and the abundance of universities, art schools, and philosophical or technological thinktanks.
Government and Control
Ysi has minimal corporate influence. The government is truly in control here. That government is the UFSS, who seized direct control of much of the Large Magellanic Cloud in the First Magellanic war. The UFSS is fair to its citizens, and most people under the UFSS live fairly good lives. Ysi is near the UFSS frontiers, but the local government has done well in keeping the area prosperous independently, the threat of a Ysau revolt a distant memory now.
Capital City: Ysander
Ysander began as a palace for ancient Ysau king Ysander. Initially it was meant to exert power and force against a rival kingdom in another forest, but throughout the construction process a larger and larger city began building up around the palace. The king ordered wells drilled to support the workers, and found a vast underground aquifer of fresh water. After that point, the palace became a boom town. Ysander would go on, in part thanks to the power he gained from having such a central and prosperous city, to be the first Ysau monarch to conquer another forest. Over the Ysau's long history, Ysander's descendants would become the first rulers to unite all the forests under one government, and even more distant descendants ruled the nation when it came into conflict with the Confederacy millenia later.
Nowadays, The Palace of Ysander has grown to become the largest city on Ysi's surface, taking up almost 30% of it's land area on it's own. It houses 40% of the planet's populace, and is a cultural, economic, and scientific center for much of the Large Magellanic Cloud. The governor of the sector operates out of the city, as do the provincial court and legislature.
Ysi formed over 5.4 billion years ago. A hot ball of rock close to it's star, it eventually cooled down enough to keep anything on it's surface from burning immediately, and much of the planet's mass was made up by (now evaporated) water ice. Life took longer to evolve here than on many other planets, because obtaining nutrients and water was much more difficult on Ysi. The first lifeforms are believed to have emerged 4.7 billion years ago, and the current dominant flora and fauna evolved about 3.9 billion years ago. The Ysau, comparatively, first arose seven million years ago. In early history they formed groups of hunter gatherers who killed smaller animals and tapped flora for water and food. Approximately thirty thousand years ago, the first civilizations began to arise on Ysi.
The early societies were small cities and networks of villages in the forests who had cleared land and learned to farm moisture and grain by utilizing specific plants. These societies soon evolved into the first monarchies and empires, and for several thousand years there were many kingdoms. Sometimes a kingdom would conquer an entire forest, but never could one succeed in invading another forest long-term.
That was until Ysander. With a much closer and more defensible base of operations and supply line, troops could be reequipped and reinforced much faster, and this led Ysander to conquer a second forest, cementing his kingdom as the dominant power of the planet.
Over the next few centuries, the rest of the planet was slowly pacified. There were speed bumps- other nations realized the advantages of drilling for aquifers, and defeating the new Kingdom of Daevalt in the central deserts took a centruy on it's own. But after five hundred years of conflict, the Ysau entered an unprecedented age of peace. The planet was slowly industrialized. The Ysau, like many nations, encountered a climate crisis in the wake of their industrial revolution, and resolved it before it became catastrophic. Their population and technology grew, and the planet became more and more a city before a world. By the time of the Magellanic war, it was the capital of an interstellar empire of billions of stars, and the center of Ysander was filled with elegant government buildings and homes of the noble and wealthy.
Ysi's furthest fall would come at the end of the Ysau resurgence period of the war. The planet escaped mostly unscathed from the first war, as the military had mostly fled to outer colonies and dispersed. This was not the case after the resurgence. In this time period, the Ysau briefly retook their homeworld as a part of their main counteroffensive, and they decided to stand and fight when the Confederate fleet arrived. The battle was bloody, but ultimately a foregone conclusion against the overwhelming force of the Confederacy. Ground invasion left much collateral damage, and Confederate commanders, among them leaders of the Alech Dominion, advocated and then performed a bombardment that leveled the governmental, military, and industrial districts of the planet. Civilian casualties were high, but revolt was brutally suppressed by a Dominion garrison. In the years since, Confedearte troops were slowly pulled out of the area, and with the Ysau adequately pacified, the area has mostly been left to govern itself.