Which writing system was adapted for the Mongolian language under Genghis Khan?

Which writing system was adapted for the Mongolian language under Genghis Khan? The answer is the Uyghur script, more precisely the Old Uyghur alphabet. Around 1204, after defeating the Naimans, Genghis Khan is traditionally said to have captured the Uyghur scribe Tata-tonga and ordered him to teach writing to the Mongol ruling family.

The Mongols adapted the script to record their own language, creating the traditional Mongolian script. It was derived from a script ultimately related to Sogdian and Syriac writing traditions. The new system became essential for imperial administration, law, diplomacy, taxation, and record-keeping across the expanding Mongol Empire.

Traditional Mongolian is visually distinctive because it is written vertically from top to bottom, with columns proceeding from left to right. This unusual direction developed when the Uyghurs rotated their earlier horizontally written script, likely under the influence of Chinese writing conventions.

Arabic, Tibetan, and Chinese scripts were also used in Mongol-ruled territories for particular languages and communities, but they were not the principal script adapted specifically for the Mongolian language under Genghis Khan.