[Turin Turambar]

Tolkein speaks of the two other istari Pallando and Alatar who went to the East and failed their quest like Radagast and Saruman did. My question is how far into the East did they go? Were they the reason the Easterlings were allied wih Sauron, like Saruman's Dunlendings, or did they go all the way East to Cuivenen for some reason? It seems they are forgotten and are mentioned only in the UT. I'd like to know your thoughts on what role they played during the War of the Ring and after and where exactly they might have went.