With the Great Khan's death, his once-glorious fleets were destroyed, and the Golden Holy War Khanate he had built through conquest and outright plunder fell apart.
The member states of the Sea of Stars Community reached a consensus: they would not recognize the Golden Holy War Khanate's territorial claims, and every nation had the right to reclaim the systems occupied during the war.
After all, the Milky Way Galaxy had already been carved up. Most of the Great Khan's territory had been ceded by others, so it was entirely reasonable for each nation to take back its own lands.
As for Minamar Specialized Industries and the Human Federation, most of their populations had already been absorbed into Xi Yan's domain. Neither had a functioning government anymore, so they could be considered fallen nations.
Xi Yan could reasonably and legally acquire all their territory, more than doubling the Empire's borders in one stroke.
The only problem now was to reconquer those lands, bring every last one under firm control, and adapt them to the Empire's various policies.
Fighting wars was easy. No Stellaris player was incapable of that. But postwar reconstruction and planning for occupied planets were another matter entirely.
Usually, when a war ended, unless you had enabled an extermination policy or simply bombarded everything with a Colossus, you would find a pile of occupied planets cluttering your interface.
Every one of those planets had high devastation, low stability, high unemployment, poor housing conditions, and countless destroyed buildings. The whole mess needed sorting out, and the low stability could even trigger rebellions.
Of course, for a proper Stellaris player, it all came down to having too many pops. Suppose we exterminated everyone on those planets, or culled them until only a hundred million remained. Then none of those problems would