The Horibe clan originated from the Omi Genji Sasaki clan, and was a branch family of the Mabuchi clan founded by Hirosada MABUCHI, Sadatsuna SASAKI's son.
そもそも堀部氏は近江源氏佐々木氏族で、佐々木定綱の子馬淵広定より始まる馬淵氏の支族である。