Angry Balls: Languages With Very Few Vowel Phonemes

Angry balls says you talk about languages with very few vowels and languages of the northern Caucasus region weren't mentioned. Some linguists argue that certain of those, Oubich was one of them, have only one vowel phoneme as there are no minimal pairs to separate the vowel sounds used. The more mainstream ones such as Chechen or English have a normal number of vowels like five.