MCU continuity glitch
In Thor: The Dark World, we learn that Odin's father Bor led the armies of Asgard to defeat the Frost Giants in Norway because it was his dominion as part of the Nine Realms. Then in Thor: Ragnarok we learn that Odin and his first-born daughter Hela created the Nine Realms in a bloodthirsty frenzy of conquest.
How could Bor defend something that is yet to be created?