Cui Yan
It is not known when Cui Guicong was born. He was from the "Greater Branch" of the prominent Cui clan of Qinghe (清河, in modern Xingtai, Hebei), and his male-line ancestors originally claimed ancestry from the ruling house of the Spring and Autumn period state Qi. Cui Guicong's traceable ancestry included officials of Han Dynasty (including Cui Yan), Liu Song, Northern Wei, Northern Qi, Sui Dynasty, and Tang Dynasty, although neither Cui Guicong's grandfather Cui Cheng (崔誠) nor his father Cui Huang (崔黃) were listed with any offices.