Abaoji in the context of "Chinese era name"

The Liao dynasty (/ljaʊ/; Khitan: Mos Jælud; traditional Chinese: 遼朝; simplified Chinese: 辽朝; pinyin: Liáo cháo), also known as the Khitan State (Mos diau-d kitai huldʒi gur), officially the Great Liao (Chinese: 大遼; pinyin: Dà Liáo), was a Khitan-led imperial dynasty of China and empire ruled by the Yelü clan that existed between 916 and 1125. Founded around the time of the collapse of the Tang dynasty, at its greatest extent it ruled over Northeast China, the Mongolian Plateau, the northern part of the Korean Peninsula, southern portions of Siberia, and the northern tip of the North China Plain.

The dynasty rose from the consolidation of power among the Khitans in the 8th century and their expansionist campaigns in the latter half of the 9th century. Eventually the Yila chieftain, Abaoji, became the leader of the Khitans and proclaimed a Chinese-style dynastic state in 916. The Liao dynasty launched multiple military campaigns against neighboring states and peoples including the Kumo Xi, Shiwei, Tatars, Zubu, Khongirad, Balhae, Goryeo, Later Tang, and the Song dynasty. Its conquests include the Sixteen Prefectures (including present-day Beijing and part of Hebei) by fueling a proxy war that led to the collapse of the Later Tang (923–936). In 1004, the Liao launched an expedition against the Northern Song dynasty. After heavy fighting and large casualties between the two empires, both sides worked out the Chanyuan Treaty. Through the treaty, the Liao forced the Northern Song to recognize them as peers and heralded an era of peace and stability between the two powers that lasted approximately 120 years. It was the first state to control all of Manchuria.

The Yelü clan (Khitan: , spelled əy.er.uu.əld, pronounced Yeruuld; Chinese: 耶律; pinyin: Yēlǜ), alternatively rendered as Yila (Chinese: 移剌; pinyin: Yílǎ) or Yarud, was a prominent family of ethnic Khitan origin in the history of China. The clan assumed leadership of the Khitan tribal confederation in 907 when Abaoji was made khagan. In 916, Abaoji founded the Liao dynasty. After the fall of the Liao dynasty in 1125, members of the Yelü family continued to play significant roles in history, most notably for ruling the Western Liao and during the Mongols era of conquest in the 13th century. Yelü Chucai, the last recorded person to be able to speak and read the Khitan language, is notable for advising Genghis Khan in the Confucian tradition.

The Yelü clan established numerous dynastic regimes in Chinese history: the Liao dynasty, Northern Liao, Western Liao, Eastern Liao, and Later Liao. In particular, the Liao dynasty and Western Liao were powerful empires that had significant impact on regional history.