Chōshū Domain
Yamagata was born in Nagato Province in Chōshū Domain (present-day Yamaguchi prefecture, as the son of samurai Katsu Kanesuke and the Toshiko, the elder sister of Yamagata Aritomo. As the latter had no children, he was adopted by Yamagata Aritomo in 1861 to carry on the family name.