History of Liao
Yelü Dashi was a minor member of the Liao dynasty's imperial Yelü clan and an eighth generation descendant of the Emperor Taizu of Liao. His date of birth is not entirely clear but may have been in either 1087 or 1094, according to various accounts of the history of Liao. The "History of Liao" describes him as "well-versed in Khitan and Chinese scripts, excelled in riding and archery, and had passed the highest imperial examination in the fifth year of the Tianqing era" (1115 AD).