NavMesh Areas
NavNesh Areas can affect NavNesh generation and agent behavior/pathing.


You can also specify the Area for a link component.

Limitations
Currently there is a limit of 24 NavMeshAreaDefinition, but you can assign them to as many Area Components as you like
Static areas are basically free.
Moving areas are a bit more expensive, but you should be able to have at least a couple of dozens of them.