Why is Tribal Sovereignty important to tribal communities?

Why is Tribal Sovereignty important to tribal communities? 

Write  a 2 page essay discussing what you have learned from the readings,  discussions, activities and lectures from the Unit concerning tribal  sovereignty. The essay should discuss what upholds tribal sovereignty  and how tribes are using tribal sovereignty. This assignment is intended  as an exercise to assess your current knowledge concerning tribal  sovereignty. The essay assignments will be graded on three components:  use of major concepts from readings, clarity in communication, and  insightfulness. Please see the course schedule for due dates. All  assignments must be turned in via Blackboard on the Thursday the week  the assignment is due by 11:59pm or the paper will be considered late.  Late papers are accepted for a 10% reduction, but must be turned in a  week after being late. This paper should be formatted with 1” margins,  written in Times New Roman font at 12 pt and double-spaced. Due 3/5