Tata-tonga (Mongolian: Тататунга, Mongolian script: ᠲᠠᠲᠠᠲᠤᠩᠭᠠ, Tatatungүa) was a Yugur man involved in bringing and adapting the Old Uyghur alphabet to Mongolia in what is called the traditional Mongolian alphabet (Mongol bichig or hurdum bichig). He was captured by Genghis Khan in the 13th century and soon taught the Old Uyghur alphabet to members of the court and adapted it, to match the Mongol Khalkha language, although Genghis (or Chingis) himself never learned it.
The Uyghur script was used in Mongolia until its independence from Qing dynasty China, at the beginning of the 20th century and few years before Russia introduced Cyrillic. It is still used mainly in Inner-Mongolia. In current day Mongolia, Cyrillic is the official script for the Mongolian language, and the traditional script is referred to as the Old Mongol script (Mongolian: Хуучин монгол бичиг). Today, an estimated 6 million Mongolians from China can still read the traditional Mongolian script but only 3 million from Mongolia.
The Manchu alphabet was derived since the very end of the 16th century from this Mongolian script.