I have a friend who is a history teacher who is toying with the idea of having his students make a map of history, like this:
http://www.slate.com/blogs/the_vault/2013/08/12/the_1931_histomap_the_entire_history_of_the_world_distilled_into_a_single.html
If you were in his place, what software would you use to make a professional-looking map?