The Delta Aquarii Nebula is one of dozens of known life-bearing nebulae. Inter-galactic travel is often too inconvenient and expensive for sustained use, so most inhabitants are descendants of travelers from thousands of years ago, bringing along knowledge and technology allowing inter-planetary travel, which is far easier and safer. Over time, as satellite communications reached neighboring planets, it's often discovered in these nebulae that the first travelers weren't the first to settle in the area. This, naturally, created alliances and tensions early on, and it wasn't uncommon for nebulae to go "dark" as like civilizations are wiped out by conquering neighbors or other travelers like themselves. Thankfully, some have managed to hold on long enough for the cloud to stabilize, and through diplomacy and negotiations, are able to become established as a fully civilized nebula.
Delta Aquarii is currently in a period of grateful stability after numerous deadly and often stalemate-inducing wars. While the Vesk are considered the most outwardly hostile, other races have shown to be ruthless in other ways, whether through dominating megacorporations or clever subterfuge and trickery. Finally, through the tireless efforts of numerous diplomats across all races, a collection of treaties known as the Delta Aquarii accords came into effect. It divided the nebula into distinct areas of more-or-less de-facto racial space, allowing free travel and guaranteeing basic freedoms while still ensuring autonomy. The final straw was a climactic battle that took place in the very center of the nebula, resulting in so much destruction, advanced weaponry, and radiation that the area has become known as a 'Dead Zone.'
Planets within the zones belong to such, and while many have been discovered and either settled upon or industrialized, there are still numerous unknown planets yet to be discovered within the nebula.