 In the last thousand years, sons of an imperial male and a Fujiwara woman have been preferred in the succession.The five Fujiwara families, Ichijō, Kujō, Nijō, Konoe, and Takatsukasa, were the primary source of imperial brides from the 8th century to the 19th century, even more often than daughters of the imperial clan itself.Fujiwara daughters were thus the usual empresses and mothers of Emperors.