Can you explain these plot holes in Lord of the Rings?

As for the second point, it's been a long time since I read the books (basing my answer off of them since the movies do not elaborate on nearly as much), but I'm pretty sure Mordor's forces took the South first and marched northward in effect surrounding them. Again, I'm not entirely certain. I know for sure that the elephant riders (cannot for the life of me remember their names) come from a southern kingdom.