三河国
The Matsudaira clan originated in Mikawa Province. Its origins are uncertain, but in the Sengoku era, the clan claimed descent from the medieval Seiwa Genji branch of the Minamoto clan. According to this claim, the founder of the Matsudaira line was Matsudaira Chikauji, who lived in the 14th century and established himself in Mikawa Province, at Matsudaira village.