The Khitans originally had no writing, but they were engraved with wooden deeds to keep records. Yelu Abaoji made thousands of characters from the side of Renlu Bugu and Tulu Buke according to the imitation of Chinese characters, which were called "Khitan characters". After the Khitan characters were made, they were immediately promulgated by Abaoji on January 25, 920 (the second day of the first month of the fifth year of the Book of Liao Shenshu). Later, Abaoji's younger brother Diethorn learned Uighur and created "Khitan small characters". It is said that his characters are "small and coherent", which may have been made of pinyin letters.

yelu abaoji