I believe the answer is: : I see men of my own race treated as outlaws and driven from country to country, or shot down like animals.
By conveying that people in his race was treated as animals, Chief Joseph appeal to audience's emotion and evoke sympathy toward the struggle of people from native American descents due to the conflict that they faced with the American Colonists.
The main purpose of the Navigation Acts was to keep wealth and trade within the British Empire.