How do I filter down on multiple taxonomies?
For this case, exposed filters are the wrong approach.

You can do this by making a contextual filter that operates on your region vocabulary.

Assuming your view is set to display taxonomy terms, I would do the basic configuration like this:


Add a contextual filter of type Taxonomy term: Term ID.
Set When the filter value is not available to Display a summary.


When you do this, you should get a page that list the regions if you have not selected one yet but lists data if you have selected a region.