Avamar died a couple months before I joined. Eleador even longer before. Avamar, however, was part of a larger war. It wasn't just Sirion v. Avamar.
Sure, it was Oligarch, Perdan, Avamar, Rancagua vs Sirion, Fontan, Old Rancagua + Eleador on both sides at different times from what I remember but you cannot exclude everything that is a part of a larger war. There is almost never one versus one in bm.
Speaking of dead realms, since I have at times been paused, how did Old Rancagua die? Who killed Fontan? Who killed the realms on the islands that existed previous to OI (I think I missed one..like Kalmar Islands dying?).