Mongolian Ba and Writing Down a Vertical Spine

The most immediately visible fact about traditional Mongolian is that it runs down the page rather than across it, and that its columns are ordered from left to right. Both halves of that matter. Vertical writing is not unusual in itself, since Chinese, Japanese and Korean have all been written in columns, but those columns run from right to left, and Mongolian runs the other way. The direction is inherited rather than chosen. The alphabet came from Old Uyghur, which was written horizontally from right to left in the manner of its Aramaic ancestry, and was rotated a quarter turn counterclockwise to be written in columns, which turns a right to left line into a top to bottom one and leaves the columns advancing to the right.

A script's direction is one of the most conservative things about it, and this one preserves the evidence of two earlier arrangements at once. There are practical consequences. A Mongolian text sits awkwardly in a horizontal page layout and awkwardly on a screen, which is one reason digital support took a long time to mature. Bilingual signage in Inner Mongolia, where the script is in continuous everyday use, characteristically pairs vertical Mongolian with horizontal Chinese, and the two occupy the same sign in quite different ways.