辽史
Yelü Bei was born in 899, before the founding of the Liao dynasty. His father was the Yelü clan chieftain Yelü Abaoji, and his mother was Yelü Abaoji's wife Shulü Ping; he was their first son. He was described by the "History of Liao" as intelligent and studious in his youth, with a relaxed appearance and a loving heart.