Different SF writers have different names for their interstellar civilization. Ian M Banks has the Culture, Star trek has the Federation and the Dominion, empires and kingdoms have been used too. The Polity was my own particular take on this. I wanted something big, sprawling and complicated in which I could set just about any SF story. Its inception was in numerous short stories where similar technology might be used, similar alien life, agents, characters and gradually grew almost like a crystal forming. Runcible gates where a hat-tip to the ansible, but grew into a science whose nomenclature evolved from the poem The Owl and the Pussycat by Edward Lear (a tachyon, for example, is called ‘pea-green’). I wanted my Polity linked up by spaceships and instantaneous matter transmission and the runcible gates are the latter, giving people the ability to step across light-years in an instant.