The Doonnarh and their wars
In order to rebuild and reclaim their planet after the devastations of the civil wars, the Doonnarh had to put their collective minds to further technological advancements. Back then, they weren't isolated from the entire galaxy yet, so they travelled extensively and inquisitively in search of assistance.
They came across more trouble than worth, in the long run, even though the cultural exchange with some races provided them with the technology that is heard of today.
The Bubble is one of the first feats that went up as soon as the Doonnarh progressed. It may have had something to do with what they saw occurring in the galaxy, or maybe they were projecting their own hostile behaviour onto others. Overall the Doonnarh exhibit more introverted tendencies as a race. Which has everything to do with how they crawled out of the caves underneath the surface and onto the land they would eventually destroy.
Where they got the schematics for the Bubble, how does it work - all of these things are closely kept secrets. A certain elite scientific cast is monitoring the now-ancient protective cloak.
The next interesting feat to kick in was the invention of time travel by the Doonnarh and their advanced studies of temporal mechanics.
Truly, why waste time exploring the hostile galaxy nearby when you can apply time-travel principles and covertly sneak around other dimensions and timelines? First, they were simply curious to find new paths to progress, making deals with the other Doonnarh from the neighbouring time-space layers. Soon, however, they discovered that the Doonnarh might be somewhat consistently unfriendly or unwilling to cooperate.
Then, the Doonnarh temporal wars began and, technically, are being carried out to this day as they slowed down to mutual jabs. The Doonnarh agents would time-travel, steal from and attack each other, all fighting to become the best, most progressive Doonnarh.
Life would play a cruel trick on them when the next generations would realise - extensive time travel doesn't mix with their physiology. Lots of new diseases emerged as a result of being constantly exposed to temporal particles. Long missions to other sides caused long-term damage and trauma. Along with many of the Doonnarh becoming, let's say, allergic and sensitive to the particles and the radiation.
This caused the conflicts to slow down crawl and led to the Doonnarh's current policy where they would employ agents from other races to assist them in their agenda.