I'm currently finishing my last semester as an undergraduate history major. Recently I've decided that I'm interested in graduate school and getting PhD. After talking to my professors, the general concensus is that I need to learn the language of the area that I'm interested in studying. I'll be European history and at some point I would like to study Scandinavia because I'm fascinated by the Vikings. So my question is what language should I learn i.e. Norwegian, Danish, Icelandic, etc.
Well, if you want to study the Vikings, you actually need to learn the languages that the texts about them are in. So we're talking Latin and Old Norse, not Danish, Swedish, or Norwegian. It seems like you're in an Anglophone country, so whether you need to learn the modern languages as research languages probably depends a lot on what you want to do. To be brutally honest, the academic communities of those countries are fairly insular, and you may be engaging most scholars in English, anyway. I don't know enough about Viking history to know that for certain, but that's my sense.
A lot of PhD programs in the US require medievalists to pass language exams in either French or German, as well as Latin and an area language (ie Old Norse) (some even require French + German + Latin + Area Language). So that's a program specific wrinkle.
I actually have a question that sort of applies, when I was looking at schools to get my masters in a program for classical greek history the requirement was also French or German rather than koine or medieval greek. Why is that so? Is it perhaps the original koine greek documents no longer exist and only copies or opinion pieces of French or German exist?
Its kind of confusing, since most of the biblical studies are done in koine greek but I guess the lack of other classical documents that are not religious based is tied to Justinian and the closing of the school of Athens/Platonic academy.