The Senchus and the Duan name Fergus's father as Erc son of Eochaid Muinremuir. A Middle Irish genealogy of the kings of Alba gives an extensive genealogy for Fergus: m. h-Eircc m. Echdach Muinremuir m. Óengusa Fir m. Feideilmid m. Óengusa m. Feideilmid m. Cormaicc, and a further forty-six generations here omitted. While it was suggested some believe Fergus claimed lineage to Arthur, the historian John Morris has suggested, instead, that Fergus was allowed to settle in Scotland as a federate of Arthur, as a bulwark against the Picts.