I want few actors not to enter an area NavMesh

I have few actors that are enemys and I want them not to enter or avoid in total some areas where, the “good” area is.
How can I do that?

For anyone looking this up, this is actually a self-answering question because if you don’t put a NavMesh over an area, enemy AI’s won’t enter that area.

NavMesh’s define where enemy AI’s will go, not where they will not go.