According to Freud's psychoanalytic theory, all psychic energy is generated by libido. Freud suggested that our mental states were influenced by two competing forces: cathexis and anticathexis. Cathexis was described as an investment of mental energy in a person, idea, or object.
The first one is the Treaty of New Echota
the second one is the Indian Territory
The main reason why slavery spread was that people owned large pieces of lands and they needed cheap work force. What better for them than to have a work force that was strong and completely free.