Mongolian Ka ᠺ

Ka writes a velar stop distinct from the harmony governed pair in the native part of the alphabet, and it is the twenty-seventh letter, the second of the ten added for foreign sounds. Unicode encodes it at U+183A. The native alphabet already has two velars, one for back class words and one for front class words, and the choice between them is not free: it follows from the vowels of the word. That arrangement works perfectly for Mongolian and fails immediately for a borrowed word, which arrives with a velar of its own and no harmony class to assign it to.

A separate letter standing outside the harmony solves the problem by refusing to participate in it. The same logic produced the aspirated velar that follows and the fricative further along: each covers a velar distinction that foreign vocabulary requires and Mongolian does not make. Chinese loanwords are the main reason this particular letter exists. A reader meeting it knows at once that the word is not native and knows roughly where to look for it, which is the incidental benefit of keeping the added letters separate from the inherited ones instead of overloading the existing shapes. The alternative would have been to write borrowed velars with whichever native letter the surrounding vowels happened to demand, which would have made the harmony class of a foreign word into a spelling decision and produced a different written form of the same word in different contexts. Adding a letter was the cheaper answer.

Chinese words have entered Mongolian steadily for centuries, by way of trade, administration and, in Inner Mongolia, daily coexistence. Writing them in the traditional alphabet is not straightforward. Chinese syllables are built to a pattern Mongolian does not share, with initials, finals and tones, and a Mongolian alphabet designed for a language with vowel harmony and a modest consonant inventory cannot represent them without either loss or extension. Several of the ten added letters were supplied for exactly this, including this velar, the dental affricate, the voiced sibilant and two letters that stand for whole syllables rather than for single sounds. That last device is worth noticing, because a syllable letter in an alphabet is an anomaly: it means the tradition judged the sound impossible to build out of the letters available and reached for a single sign instead.

The pressure was practical rather than literary. Names, offices, goods and places had to be written down correctly in documents that would be read by people who needed to find them again, and an alphabet that could not do that would have been extended sooner or later whatever anybody thought about it. The Buddhist literature exerted the same pressure from a different direction and at a much greater scale, which is why the two efforts, the letters for Chinese and the apparatus for Sanskrit and Tibetan, sit side by side at the end of the same alphabet.