In Game of Thrones, how difficult would it be to invade the Vale of Arryn through The Bite?

Question

My idea of the Vale, and the reason why it's considered impregnable without dragons (or maybe boats), is because of the bottleneck in the Bloody Gate; however, looking at a map of the area, it seems that it would be easy to bypass that bottleneck by entering the Vale through The Bite. It would be a longer walk to The Eyrie, but considering it wouldn't be that much longer, it looks like an obvious choice for an attack.

I'm assuming there's more to this than what I know from watching the show and looking at a map, so my question is: are there plausible reasons that would make The Bite a less preferable entry point than it looks at face value?

Answer 1

What map are you looking at? And what are you referring to as The Bite?

On the maps in the books I have (which look like this), and this HBO map, and the fan-made "interactive map" web site, The Bite refers to a body of water to the north, and would land you on the north coast, and involve crossing at least one set of mountains or forest and at least one other river and/or body of water before reaching more mountains on the north side of the Vale of Arryn and having to cross those too.

It looks like it might be possible to invade by sea from the east, though.

Also Tyrion seemed to think his mountain folk could get into the vale via the mountains.