He was echoing the earlier work of Henry Morris, when he defined the wider county of Roscommon:
It is an inland island. The Shannon and Lough Ree guard its eastern frontier of seventy miles. The Bradlieve and Curlew mountains, Lough Arrow and Lough Ce protect it on the north; while its western frontier is enclosed within Lough Gara, the river Lung, and the river Suck, leaving only a gap of less than ten miles without water protection, and a succession of small hills serves to fill this gap. 
Dr. Brady went on to refer to Rathcroghan as the “cultural heartland of the province” (of Connacht). It is within this landscape, a complex area of multi layered occupation , from earliest human settlement right through the history of Gaelic Ireland, that the mythologies of two major mythological female figures were created, and stayed with us right to modern times.
These being, of Course, Queen Medb of Connacht, instigator of the Táin Bó Cuailgne, and the Morrigan, Goddess of Battle and Prophecy... among other things.
This is the landscape I call home, here in the West of Ireland, and these are the sovereign Goddesses of this land - above and below. This is the secret heart of Connacht.
 Henry Morris (1932), Studies: An Irish Quarterly Review, Vol. 21, No. 81, pp. 7-19: p. 9.
 DP Medieval Rural Settlement Project