I too am trying to trace my gg grandfather, Timothy Feehan from Co. Tipperary Ireland, I have found that the Feehans come mostly from north and east Tipperary and surrounding counties(Kilkenny to east, Limerck and Clare to the west and Kings and Queens(modern day Laois and Offaly)to the north. A region around Thurles from Clonmel to Kilkenny town to Birr To Limerick town would cover most of them. This is still a large area, but does narrow it down a bit. Hope it helps. Good Luck in your search.