It may be worth keeping your eye on the world's forums, see if anything is mentioned about the diplomacy of the tribe you are interested in. Alternatively, you could go down the path of espionage. Find a player who would be willing to spy on the tribe's forums and diplomacy page for you and get you a screenshot of their enemies list.
Convince somebody in your tribe to tell you there Diplomacy list. Or try get one of your members from your tribe into theres in a convincing performance of changing there alliegence to become your spy. Or just ask. :icon_idea: