Historians: which language has served you best?

[Jolt]

I have most experience with Ancient history where the main languages are of course Latin and Greek when it comes to ancient languages and English and German when it comes to the modern languages. Now I'm not sure what the most important modern languages are in Medieval history, though usually the language from the area you want to study are important. Latin you usually can learn at university, you will have to learn medieval/post classical latin at university anyway. Well at least if you really want to take it up serious with the languages, as medieval latin is quite different. A lot of words have shifted meanings for example. If you are interested in west-European history picking up german and or french is not a bad idea. However as has been said before English is the most important one, as it has most publications is the language used in most lectures even in foreign countries, and a lot of publications get also translated.

Still, there is an colossal amount of works which do not get translated into English. For instance, my major area of interest is the Portuguese Discoveries, and if I wanted to stick to English, I wouldn't get nearly anywhere. Practically every credible primary and secondary source is written in Portuguese, and the major works written in English about the subject speak in a general manner (With differing levels of objectivity) of the Portuguese discoveries as a whole, and the major events of it. Things like the Portuguese presence in Macau and China during the 16th-18th, or Indian Portuguese Empire during that time (Which could very well allow for a master's thesis), giving just two examples, you won't get anything in English, or what you can get from it, you can easily get much more information in Portuguese.

So yeah, I'd say history is far, far, from being English dominated.

EDIT:
Ancient Egypt era: Egyptian hieroglyphs and derivates
Ancient Babylonia/Assyria: Akkadian cuneiforms
Ancient Greece: Koine Greek (For Alexandrian and Diadochi periods, learning Akkadian and/or Elamite cuneiforms can also be useful. There is a bounty of information written down from primary sources in those languages)
Roman era: Classical Latin
Dark Ages/Medieval era: Medieval Latin and the language of the area you're specializing in.