Seiwa Genji
The is a Japanese dynasty that was formerly a powerful "daimyō" family. They nominally descended from Emperor Seiwa (850–880) and were a branch of the Minamoto clan (Seiwa Genji) through the Matsudaira clan. The early history of this clan remains a mystery. Members of the clan ruled Japan as "shōguns" from 1603 to 1867.