As Naito clan in Mikawa was the vassal family offudai (a daimyo in hereditary vassal to the Tokugawa family) served the Matsudaira clan (Tokugawa clan) since Ienaga's grandfather, Ienaga, who was the son of Kiyonaga in later life, served Ieyasu TOKUGAWA and succeeded to the head of the Naito family from the older brother-in-law Nobunari.
三河の内藤氏は家長の祖父の代から松平氏（徳川氏）に仕えた譜代の家臣の家柄であり、父・清長が晩年になって儲けた子の家長は徳川家康に仕え、義兄の信成から内藤家の家督を譲られて跡を継いだ。