Blue airy giant planet and people.
Mix between byzantine empire and harry potter mystics
lives are extremely long. Lowest population of the rebellion.
Deep issues of ageism. Old hold damn near everything. Young seen as naive and inexperienced to run things.
Now most of their youth seem to have taken to the stars, leaving their homeworld in an even greater population crisis.
Society is stable to the point of rigidity.
Put up little resistance for fear of annihilation
Find other planetary environments unpleasant and noxious.