What script did Genghis Khan adopt for writing the Mongol language?

Genghis Khan adopted the Uyghur script for writing the Mongol language. Around 1204, after defeating the Naiman, he captured an Uyghur official and scribe known as Tata-tonga, who was traditionally credited with teaching the Mongol court to use the Uyghur writing system.

The script was adapted to represent Mongolian and became the ancestor of the traditional Mongolian script. Unlike most vertical scripts, traditional Mongolian is written vertically from top to bottom in columns that progress from left to right. Its deeper origins reach through the Sogdian script to the Aramaic writing tradition.

The adoption gave the expanding Mongol state a practical system for recording decrees, correspondence, laws, and administration. It also helped the empire govern multilingual territories. The script should not be confused with the later ’Phags-pa script, which Kublai Khan commissioned in the Yuan period for use across the empire. Chinese and Tibetan scripts were also used in parts of Mongol-ruled Asia, but neither was the original official script adopted for Mongolian by Genghis Khan.