What was the official language used across European monarchies in the XII century?

Question

I have been reading about European history in the XII century and I am finding out that several of the modern day languages hadn't yet evolved to what they are now: Langue d'oïl was still being used in France & Belgium, Old Saxon was still in vigor as well as Anglo-Saxon and Old East Slavic / Old Russian. Was there an "official" language among monarchies just as English is nowadays for most governments? There were already agreements, marriage pacts and even crusades planned among different monarchies so they must have established communication somehow... I'm leaning towards the equivalent of French at the time, however I couldn't get any official sources to confirm this. Wikipedia lists some of the monarchs of the time here: [12th-century monarchs in Europe](http://en.wikipedia.org/wiki/Category:12th-century_monarchs_in_Europe)

Answer 1

Medieval or Vulgar Latin was the Holy Roman Empire's lingua franca.