Add content in sidebar relative to content in main page

I'm a Drupal newbie trying to set up my first site, a travel site.

When I have a content item about place 'a' I want to have ads that relate to country of place 'a' appear in the right sidebar. Same for place 'b', 'c' etc and country 'b', 'c' etc.

My taxonomy terms structure is as follows

Destination
-Country 'a'
--Place 'a'
--Place 'b'
--Place 'c'
-Country 'b'
--Place 'd'
--Place 'e'

Content can be at country or place level, each country only has one set of ads. All content should have ads relating to the country of the content in the sidebar.

I've created a right ads block to appear in the right sidebar, from there I get stuck.

What module I can use to do this? Any tips are greatly appreciated.