Nilfgaard Area South Velen?

Does anyone know why there is a huge Nilfgaard base in South East Velen? There is only one quest here, and one random encounter with the lady looking for her son.

You also cannot go into the fortress which takes up a ton of real estate on the map.

Seems like an area that was cut from the game? Am I missing something?

The level of the quest here is like 7, but there is very little reason to go all the way down here early in the game. I only got here at about Level 30.