Let us first consider what our information is regarding the Two Fifths comprised in Munster. Keating gives two alternative divisions of Munster to form the Two Fifths. In one division, the dividing line runs north and south, from Limerick to Cork Harbour. This delimitation seems to be based on the ancient extent of Munster, which did not include County Clare. The second partition of Munster, according to Keating, is by a line running from Tralee to Slieve Bloom, a very unlikely boundary, as will be evident to anyone who tries to place it on the map. The portion south of this line, we are told, was the realm of Cú Raoi, and the portion north of it was the realm of Eochaidh MacLuchta. These two names belong to the Ulster cycle, and we should expect the division connected with them to hold good in the topography of the Ulster tales, but we shall find that the Ulster tales speak of Eochaidh MacLuchta as king of all Munster and speak of Cú Raoi as a great Munster hero, but not as king of half Munster. That is not the whole story. Keating tells us that Tuathal Teachtmhar, when he became king of Ireland, established a small domestic realm for himself in the centre of Ireland, around Uisneach, by cutting off a section from each of the Five Great Fifths, and that the boundaries of all five, until his time, met at one point, the rock called Aill na Mireann, on the slope of Uisneach hill. Look at the map of Ireland, bearing in mind that the county Clare was not at that time and long after it a part of Munster, and ask yourself what possible dividing line between two kingdoms of Munster could have terminated in the hill of Uisneach, which stands ten or twelve miles westward from Mullingar.