Okay - i think I found a solution to this. allan.walker.0 created the Natural Earth map several versions ago in Tableau - see here: [World] Natural Earth – Countries « Tableau Mapping
I downloaded this workbook and then added in the included Tableau World Indicators data to create a new view showing World Indicators on this natural earth map. I created a relationship between the data sources on Natural Earth Admin - [Name] = World Indicators - [Country] and then I was able to cratee a view showing any of the measures from the secondary data source on top of the Natural Earth map.
maybe Allan has a better suggestion than from back in the Tableau 7.0 days but this might get you going so I am sharing.
The attached .twbx is in version 9.3