Mongolian Qa and Harmony Reaching Into the Consonants

Vowel harmony is named for the vowels, but in Mongolian it does not stop there. The velar consonants come in a back class form and a front class form, and which one appears is settled by the vowels of the word rather than by anything independent. That makes the harmony a property of the whole word rather than of its vowels alone, and it is why grammars speak of back words and front words rather than of back vowels and front vowels. A suffix crossing onto a word must match it in both respects, presenting its front vowels and its front velar to a front word and its back series to a back word, so a single suffix may have two or more written forms with no difference in meaning.

For a reader of the script this is useful redundancy. The class of a word is signalled several times over, by the vowels that are distinguished, by the velar chosen, and by the form of any suffix present, so an ambiguous vowel shape in the middle of a word is usually resolved by evidence elsewhere in the same word. Systems of this kind are found across the languages of northern and central Asia, and the resemblance among Turkic, Mongolic and Tungusic languages in this respect is one of the observations that started a long and still unsettled argument about whether they are related or merely neighbours.