I think you misread my email. I said the tests gave evidence that you are indeed related to the Browns. However, your question was about your relationship to a specific person named Chief John Ross, and you being related to the Brown family doesn't prove any relationship to that specific person. That's why I suggested Y-DNA since I assumed your surname was Ross and he would be in your direct male line (father's father's father etc.).
The more important thing to remember is except for maybe close matches like parent/child, a single autosomal test can't be considered "proof" of anything, especially the further back you go.