I have found several books on Irish family names. While I personally don't care much if my long-dead ancestors were royalty or sheep herders, some people apparently do. So I suggest you look for a book called "Irish Family Names -Arms, Origins and Locations" by Brian de Breffny or "Irish Families, Their Names, Arms and Origins" by Edward MacLysaght.Both of these books (and others) lend light on ancient Irish history -- and names. The Kirwans (and that's how it was spelled once it was Anglicized were one of the original true Gaelic families. They were great land owners and leaders in Galway and one of the so-called "Tribes".They were the Gaelic O'Ciardubhain sept.I found many Kirwan graves in the cemeteries outside Dublin years ago -- but that is a long way from where the original tribe lived. They were land owners before the British over ran them and took their land away. There were only two "tribes" of pure Irish (Gaelic)stock -- and the Kirwans were one of them. O'Ciardubhain can be translated (loosely) as DARK. Perhaps because the Kirwans had dark hair. My own Kirwans (from Ireland) had black hair and blue eyes. Carole S.