lyannaes:

The Known World: (some) areas of the North 

It was the North and the North alone that was able to keep the Andals at bay, thanks to the impenetrable swamps of the Neck and the ancient keep of Moat Cailin. The number of Andal armies that were destroyed in the Neck cannot be easily reckoned, and so the Kings of Winter preserved their independent rule for many centuries to come.

    - [The World of Ice and Fire] Ancient History: The Arrival of the Andals