So Rhun is one of my favorite factions just because I just love the look of the golden Armour and I just love the evil man factions in general but I am looking through the wiki and I find that Rhun Isn't even allied to Mordor. Rhun sent thousands of soldiers to support Mordors fighting against Gondor. IT even says in the unfinshed tales that possibly that wainriders assault on Gondor was possibly to allow sauron to enter back into Mordor without being noticed. So I really do think that Rhun should be allied with Mordor and not just friends. Arguably the Rhunic people even worshipped sauron.