A world map and two lists displayed on a web page are connected. Hover over "Romania" link and the Romania region highlights on the world map (jVectorMap fiddle example).
As you can imagine, the two lists can grow pretty large. How to present this in a user friendly way? Think about too much distracting graphics vs. the lack of graphic hints, wall of text vs. hidden links, desktop vs. mobile etcetera.
I've contemplated tag clouds with the continents name standing out, menu-style lists where you hover over a continent and a sublist with its countries appears.
I just want to know what's the best approach (not limited to those two I mentioned above) for displaying connected lists, from a user experience point of view: quickly finding and visualizing countries while keeping things tidy.