Check it out: http://www.jlect.com/maps/eurasia-dew.html
For all non-Japanese forms, most of the data was pulled from the Wiktionary page on the word "dew", among other sources, so there may be some inaccuracies and mistakes. As for the etymologies, I tried to find as much information as I could, but I sometimes had to guess and infer relations.
If you have any comments, criticisms or other, do let me know! :)