After the experimental terraforming of Earth's Luna into a completely livable world back in 2263, mammalkind was able to rapidly increase their spacefaring technology due to the capability to launch spacecraft much more cheaply in the moon's lower gravity. Not long after that, Mars was also terraformed and colonized. However, life was still confined to just one solar system. It wasn't until 2381 that a young prodigy by the name of Leonard Horning invented a lightweight, low energy drive capable of reaching near light speed that the planet Proxima B orbiting the twin stars of Alpha Centauri A and B was colonized.
Roughly 400 years later, a new drive was invented. The brilliant inventor Zefram Cochrane invented a 'hyperdrive'. When paired with the Horning drive, it allowed ships to travel at speeds equivalent to roughly 5000 times the speed of light by essentially pulling the vessel out of physical space and into a dimension that seemed to be a compressed version of normal space. There is no matter in this 'hyperspace,' as it came to be known, but if a craft were to travel 1 lightyear in hyperspace and then come back out, it would have traveled 5276.74172346 lightyears in 'real' space.
Once mammals had the ability to move through hyperspace they expanded too quickly for the governments back on earth to handle, causing multiple disagreements about whom the newly colonized planets would belong to. More and more of these conflicts escalated into all-out war. In a few short years, almost every government was at war, leading to the largest conflict in the history of mammalkind.
On November 11, 2823, all of the remaining governments signed a treaty ending the war and laying out how a new government, designed to avoid further conflicts would work. Each earth government would become a member of a council, joint in leadership of the rapidly expanding civilization. Each colonized planet would be put into a group with ninety-nine other planets. Every group of a hundred planets would act as a province, with their own largely independent governing systems.
This system worked beautifully well for five centuries of a mammalian golden age until a prey dominance group known as the "Sons of Sol" launched an entirely unexpected coup on the five hundredth anniversary of the end of the great war. Approximately two hundred battleships came out of hyperspace directly above the capitol on Earth while the entire planets defensive weaponry was mysteriously offline. When they took control, anyone who spoke out against the Sons' was killed. Many of the provinces fought back against them, but it was only a matter of time before the entirety of colonized space was under their control.
Every predator on every planet is forced to wear a shock collar. Taxes are higher than ever before in order to fuel an enormous military, which every planet is required to send at least 2% of its population into. If a planet doesn't agree with something, then they are placed under martial law until they did.
Two hundred years after the coup, only a few 'frontier worlds' remain free of the influence of the Sons'. Fortunately, a Resistance has appeared to defend these worlds from tyranny. The Resistance is based on a planet marked in galactic archives simply as planet 4546B, though it is more commonly known as "New Zootopia," named after Earth's largest city before the Sons' took over. While the Resistance doesn't have nearly as many resources as their oppressors, they make up for it in the skill of their pilots, and rumor has it that its engineers rival even geniuses like Horning and Cochrane in brilliance.
A few years after the Resistance arose, reports of mammals near the edge the galaxy gaining strange powers that appeared to bend the laws of physics to the limits began to appear. Because of the resources that the government put into attempting to study, and in some cases cover up, these phenomena, the Resistance was given a period of time to grow into a force that could stand its own against the oppressive government when otherwise they would have been quickly crushed by the Sons' superior military.