Mongolian A ᠠ

A is the first letter of the traditional Mongolian alphabet and writes the open back vowel, the sound at the front of the word for father in most European languages. It belongs to the back class of the vowel harmony, and because it is first in the recited order it is the letter grammars reach for when they want to state that rule. Inside a word it is written as a plain tooth, one short stroke leaning off the vertical spine that runs down the middle of the column, and it is among the simplest shapes the script has. That simplicity is also what makes it hard to read, because a bare tooth is not exclusive to this letter and the word itself often has to settle which letter is meant. Like every letter here, a takes a different form at the beginning of a word, inside it, and at the end, and those three are positions of one letter rather than three separate letters: at the head of a word it is approached by a stroke that opens the column, and at the end it is drawn out into a long tail that closes it.

Unicode encodes it at U+1820 and follows the traditional recitation order, so the alphabet a Mongolian child learns and the alphabet a computer sorts are the same alphabet in the same sequence. As the first of the back vowels, a is also half of the alphabet's most characteristic pattern: a word of the back class draws its vowels from a, o and u, and a word of the front class takes the front series instead.

The traditional Mongolian alphabet was taken up around the founding of the Mongol state in the early thirteenth century, and it was not invented for the purpose. It was borrowed whole from the Old Uyghur alphabet, which the Uyghurs had themselves taken from Sogdian, and Sogdian belongs to the family of scripts descended from the Aramaic abjad. A letter such as a therefore has a pedigree that reaches back through Central Asia to the Near East, by way of merchants, scribes and missionaries rather than by conquest. The traditional account of the moment is a small and human one: a Uyghur scribe in the service of a defeated rival was taken into Mongol service and set to teaching the script, which is a plausible enough story for how a working chancery practice moves from one court to another.

What matters more than the anecdote is what the borrowing cost and what it bought. An alphabet built for one language rarely fits another exactly, and this one did not. Sogdian and Uyghur had no need to distinguish the rounded vowels the way Mongolian does, so Mongolian inherited a shortage of vowel signs it never fully repaired. In exchange it received a cursive, joined, vertical writing with a long documentary tradition behind it, which could be put to work immediately on decrees, letters and seals for an empire that suddenly needed all three.