Yes its possible.
As long as your datasource/database has the information of the countries that can
be processed and visualized by Tableau application.
Since our earth map consists of continents including countries and cities so it should not be a problem.
So, How do i do it? I have three excel sheets and have been trying to add the sheet in the data source but its not possible ? Is there any other way? If so can you please mention?
I'm afraid you cannot use multiple excel files, try to merge the contents of your file.
But if I combine the data into one excel sheet the software will not recognize all the states of all the three countries. Is there any solution to that