Board Thread:General Discussion/@comment-6192846-20140111153519/@comment-6192846-20140526033054

It came from here. Based on the name similarity, I wouldn't be surprised if the Plain was one of the Beelzenian territories conquered by Lucifenia in their wars (along with the Tasan territories) and that Duke Demilanbu/Demilamb/Demilambu controlled that area until it was conquered.