Getting Entry By Category for Landing Pages In A Structure
You need to find a way to get the right category model to be able to receive all entries related to it.
As you didn't set up our categories to have their own URL, you could find it using the relevant slug in your URL.
Assuming that maches your categories slugs:

{% set categorySlug = craft.request.getLastSegment() %}
{% set category = craft.categories.slug(categorySlug).first() %}

{% if category %}

    {% set entries = craft.entries.relatedTo(category).limit(12) %}
    {% for entry in entries %}
        {{ entry.title }}
    {% endfor %}

{% endif %}


Another, probably more elegant way would be to access a token set via a dynamic route:

'regions/[SLUG]' =&gt; 'regions/_index'


You would now be able to access that token from a variable "slug":

{% set category = craft.categories.slug(slug).first() %}