From the townland of Graigaman, in the Civil Parish of Buolick in the barony of Slievardagh, the Kings River drains the southern side of the Slieveardagh Hills, and, flowing southeast, crosses into County Kilkenny, is joined by the Munster River before passing through the town of Callan, continuing eastwards, passing Kells, and joining the River Nore west of Thomastown.