There are 2 types of languages: those whose natives assume if spoken slowly enough with enough repetition anyone should be able to understand, and those whose natives just give up and move to mime at the first hint they’re not getting through. Tamil, like English, is type 1.
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Hungarian is very much type 1 as well, despite being completely unlike any of the surrounding languages and notoriously difficult for foreigners to learn. We do have plenty of German and Slavic loan words though, so that might be part of it.
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Those were the two official languages, but many others were spoken as well. This seems to support your theory.

