Originally the bird was thought to have come from the East - through Turkey the country, or from that region and was also thought to be the same as the guinea fowl which was already known before the turkey turned up on the plates.
A clue to this is that the French name for it is 'D'inde' - i.e.'of the Indies'
Oh and Turkey, they don't call it a Turkey.....they call it a 'Hindi' - which means 'from the East' as well. Funny old world isn't it.....