In the early Liao Dynasty, the territory was in the upper reaches of the present Liaohe River basin, and continued to expand during the Liao Taizu and Liao Taizong periods. When Liao Taizu conquered Xi (now northern Hebei), Wugu, Heishewei (now southeast of Hulun Lake in eastern Inner Mongolia), Tatar, Uighur and Bohai.
At the peak of Liao Dynasty, its territory reached the Sea of Japan in the east, Altai Mountain in the west, Ergon and Daxing 'anling in the north and Baigou River in the south of Hebei. Liao history called it "Wan Li".
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The founders of Liao State were the Khitans, who originated in Donghu. The rise of Liao was in the period of Five Dynasties and Ten Kingdoms, and the Central Plains dynasties changed frequently. Liao took advantage of the golden opportunity after the establishment of Shi Jingtang, and got sixteen states of secluded clouds, such as the northern part of Beijing, Tianjin and Hebei and the northern part of Shanxi. Later, Liao was defeated by Nuzhen, a fishing and hunting ethnic group rising in the northeast, and completely perished.
10 February 1 day (February 24th, 947), the Khitan Association proclaimed itself emperor in Kaifeng, and changed the Khitan country to Liao country, with the title of "Da Liao" and the title of "Da Tong".
References:
Baidu Encyclopedia-Liao Dynasty