As far as I know, most constellations were named after greek and roman sources. I'm not sure if it's because they were first discovered by those societies or if it was a system established by a later society. But, I'm pretty sure that stars in a constellation have no relation, other than the shape they make. In reality, those stars are ridiculously far apart. But, by drawing shapes and giving them a label, we made it possible for every day people (and future generations) to map out the night sky and find common points of reference.