The Azai clan's earliest ancestor is an illegitimate child of Kintsuna SANJO and the original surname is self-designated as of the Fujiwara clan, however, they were an old local ruling family in Kohoku and their name already appears in records in the Heian Period and Kamakura Period.
浅井氏は始祖を三条公綱の落胤とする家系伝承を持ち本姓を藤原氏と自称するが、江北に古くから土着している豪族で平安時代や鎌倉時代の記録に既に名が見える。