Latin was the language of law and the state institutions even for some time after the western Roman empire fell. In most other regards, AFAIK, Greek was more important in the eastern half.

@ ajaxfetish: what is your opinion about the piraha language in this context?
Since the first time I've read about it I can't get past my earlier impression that language and numeral skills are mostly seperate - and that the tribesmen who tried and failed to learn them failed because of their age (decreased brain plasticity) and not because of some structural impairment of language.