The Es'oi are not an ancient race, but they are the first they know to expand through the stars. Their kind has existed alone in their galaxy, never managing to connect with any other space-bound empire. That is, until they began to survey planets that had initially not shown any real use for them.
The Es'oi while needing a thin atmosphere, discovered that other species preferred varying forms of atmosphere and environments- in fact, they had found hundreds of small civilizations, just waiting to discover the stars as they had! But they could not intervene. No, the Es'oi had come to consider themselves the protectors and nurturers of these many small civilizations.
One child finally broke free from their solar system. The Es'oi curiosity peaked, and all eyes had turned to see what would happen. One of their children, who they'd oh so carefully tried to encourage their first steps, would finally join them. This civilization in specific fascinated the Es'oi. They were strange. Had unreasonable traditions. They were bloodthirsty.