Fourteen of Brackett's stories are set at least partly upon Mars, making it her favoured venue. Like the astronomical Mars, Brackett's Mars is a dry, desiccated desert world; however, it is warm enough, and has a thick enough atmosphere to support life.
The major intelligent species on Mars is one of dark-skinned, yellow- or green-eyed humanoids, outwardly very similar to Earth humans though perhaps of entirely different origins. They can be divided into two main groups: the Low-canallers and the Drylanders.