Nanbu clan
Much about the ancestry of the Tsugaru clan is uncertain. Ōura Tamenobu was born in 1550, as the adopted son and heir of Ōura Tamenori, a retainer of the Nanbu clan, based at Sannohe Castle. He succeeded his father in 1567 or 1568 as castellan of Ōura Castle, located in what is now part of the city of Hirosaki. According to later Tsugaru clan records, the clan was descendant from the noble Fujiwara clan and had an ancient claim to ownership of the Tsugaru region of northwestern Honshu; however, according to the records of their rivals, the Nanbu clan, Tamenobu was born as either Nanbu Tamenobu or Kuji Tamenobu, from a minor branch house of the Nanbu clan and was driven from the clan due to discord with his elder brother.