Answer and Explanation:
Mann's goal is to show how Indigenous peoples are no different from modern Americans in terms of the search for comfort, protection and resources. It shows that the Indians migrated to areas that could provide more comfort and supply of needs at different times of the year, they did this to maintain a stable quality of life and to have more facilities in their daily lives, in the same way as modern Americans do when they decide to move between Manhattan and Miami.
Mann wanted to show how indigenous people were not so different from modern society, pointing out this similarity that went unnoticed by many.