Let me ensure I understand your question correctly. You have a hierarchical composite list, Country and Region, where the Region list is the parent of the Country List. You need to publish a page selector just for the regions.
To do so you used a SYS module dimensionalized by the Country List.
Why are you using a SYS module to publish a page selector? You should publish the page selectors from an output module (modules that are actually displayed on the dashboard)
If you want to publish a page selector of just the regions then you have to use a module that is dimensionalized by region (not City)
Einas "Give a Man a Fish, and You Feed Him for a Day. Teach a Man To Fish, and You Feed Him for a Lifetime"