What struck me as strange is there is a similar word in Persian tundra for thunder? Now, my guess is the pronunciation in European languages changes after the Great Vowel Shift. So is that just a coincidence between the European and Persian languages? It is rare that word people would let such an assumption stand if there weren't some good evidence, see Online Etymology Dictionary.
Who has neither fools nor beggars nor whores among his kindred, was born of a stroke of thunder. ~~Romanian Proverb