According to Brown, this belonged to Cormac mac Airt (3rd century), but it is anachronistic for it to appear in the Ulster cycle (set in B.C. period).

    Then who could be the candidates?

    There is Cormac Connloinges, son of Conchobar himself, but that would not be consistent. For reading back on the source, "The Tidings of Conchobar," we learn that Conchobar surrounded himself with a glut of champions, and this was not because his fighting skills were wanting, because he was the best of fighters. It was done to ensure that Conchobar will safely sire a son. So in this period, it seems Conchobar had no son, and if he did, in the person of Cormac owner of Croda, it is decidedly odd to subject that son to peril. (Of course one can speculate this son was a bastard or had a blemish that disqualified him, etc.)

    There is also another, called Cormac, king of Ulaid, "the man of the three gifts" (Da Derga's Hostel) or simply "Cormac of Ulster", the maternal grandfather of Conaire Mó. But he is the father of Conaire Mór, lead character of The Destruction of Da Derga's Hostel. His wife however, may have slept with a bird-man.

    To recap, we have

• Cormac (1) "mac Airt"
• Cormac (2) "Connloinges"
• Cormac (3) (father of Conaire Mór)

    In T. W. Rolleston Celtic Myth and Legend available in inexpensive Dover paperback, the three above are clearly distinguished (see Rollerston, Celtic Myth and Legend, index). That may be prudent to do for the sake of organization of information.
    However, further confusing the issue, Mackillop's Dict. suggest (2) and (3) above may be identical.
    In passing one might note the resemblance between Cormac (1) "Conn's ancester" and Cormac (2) "Connloinges" to see a connection there also, perhaps ultimately derived from a Cormac, possessor of a bloody spear and shield from a lost ur-saga.