What is the setting of A Planet Called Treason by Orson Scott Card?

The setting in this book is pure science fiction. For some unspecified reason, a group of people from a home planet, ostensibly Earth in the future where space travel is possible, is exiled for some kind of Treason. They are all packed into a space ship and taken to a planet which the home world cruelly calls Treason, and which the residents of the planet have retained. This is symbolic of the general attitude of the people almost over the whole planet.