Owen, as we have seen, was never King of Ireland, but he left behind him a famous son, Oilioll[19] Olum, who was married to Sadhbh,[20] the daughter of his rival and vanquisher, Conn of the Hundred Battles, and it is to this stem that nearly all the ruling families of Munster trace themselves. From his eldest son, Owen Mór, come the Mac Carthys, O'Sullivans, O'Keefes, O'Callaghans, etc.; from his second son come the Mac Namaras and Clancys; and from his third son, Cian,[21] come the so-called tribes of the Cianachts, the O'Carrolls, O'Meaghers, O'Haras, O'Garas, Caseys, the southern O'Conors, and others. There is a considerable body of romance gathered around this Oilioll and his sons and wife, chiefly connected with the kingship of Munster. Conn's son, Art the Lonely--so-called because he survived after the slaughter of his brothers--was slain by Mac Con, Sive's son by her first husband, and the slayer ruled in his place, being the third king of the line of the Ithians, of whom we shall read later on, who came to the throne. He, however, was himself killed at the instigation of Cormac, son of Art, or Cormac mac Art, as he is usually designated. This Cormac is a central figure of the large cycle of stories connected with Finn and the Fenians. He was at last slain in the battle of Moy Mochruime. His advice to a prince, addressed to his son Cairbré of the Liffey, will be noticed later on, and, so far as it may be genuine, bears witness to his reputed wisdom, "as do the many other praiseworthy institutes named from him that are still to be found among the books of the Brehon Laws."[22] This Cormac it was who built the first mill in Ireland, and who made a banqueting-place of the great hall of Mi-Cuarta,[23] at Tara, which was one hundred yards long, forty-five feet high, one hundred feet broad, and which was entered by fourteen doors. The site is still to be seen, but no vestige of the building, which, like all early Irish structures, was of wood. Cairbré of the Liffey succeeded his father Cormac, and it was he who fought the battle of Gabhra (Gowra) with the Fenians, in which he himself was slain, but in which he broke, and for ever, the power of that unruly body of warriors. About the year 331 the great Ulster city and palace of Emania, which had been the home of Conor and the Red Branch knights, and the capital of Ulster for six hundred years, was taken and burnt to the ground by the Three Collas, who thus become the ancestors of a number of the tribes of modern Ulster. From one of them descend the Mac Mahons, the ruling family of Monaghan; the Maguires, barons of Fermanagh; and the O'Hanlons, chiefs of Orior; while another was the ancestor of the Mac Donalds of Antrim and the Isles, of the Mac Dugalds, and the Mac Rories. The old nobility of Ulster, whose capital had been Emania, were thrust aside into the north-east corner of Ulster, whence most of them were expelled by the planters of James I.