It's easy to make fun of the map tweeted by Trump today but there's a dangerous history of supremacists using phony maps to falsely claim they represent or control a large swath of their country. I saw this in Bosnia when I covered the 1990s war there. 
Before the war started, nationalist Serbs falsely claimed they owned a majority of land in Bosnia, and on that basis would be entitled to control a majority of the territory if Bosnia voted to secede from Yugoslavia. Serbs constituted about a third of Bosnia's population.
Here's a map Serb nationalists created in the 1990s and that their leader in Bosnia, Radovan Karadzic, used as evidence at his war crimes trial in the Hague a few years ago. Blue represents Serb areas -- more than 60 percent of the country, according to this map, which is false.
It's ridiculous and frightening that Trumpists are taking another page from the falsify-and-divide playbook used by nationalists in the Balkans in the 1990s. Asserting a right to represent or control territory that you have no right to -- this is a precondition for catastrophe.
Do not underestimate the emotional power of maps, particularly when they are crazy. History has shown the danger of lines drawn blithely or falsely on the borders of a nation. One thing I learned in Bosnia -- maps are not just propaganda, they are ammunition.
