If you go back far enough practically all of west Dublin was in
Castleknock 
"In regard to the first point - namely, extent of territory - it is fortunate that from various references in the State Papers, and especially from two inquisitions into the lands of Castleknock - one made in 1299 and the other in 1408 - we obtain fairly complete descriptions of the different properties held by the Tyrrells as vassals of the Crown. In general, the lands of Castleknock embraced all the territory west of the city, from Island Bridge almost to Lucan northward between the River Liffey and the Tolka, and in places even beyond the latter river.
It was a fairly intensive territory, containing probably 10,000 to 12,000 Irish acres. It embraced the Phoenix Park, and stretched as far as Clonsilla and Luttrellstown on the south , and northward beyond Blanchardstown, and apparently even to place north of the Tolka, from Cappagh to Clonee, on the borders of County Meath.
During the thirteenth century many Norman families settled on this district as dependants of the Tyrrells - or by grant from the Crown. Most of these families have given their names to the lands which they occupied either by additions of the word "town" to their surname or even by the use of the surname alone. Thus we have Luttrellstown, Blanchardstown, Pilatestown (Pelletstown), Abbotstown, Carpenterstown, Keppoge (Cappagh), etc. while some of the older names still survive, as Clonsilla, Mullaghahiddert (Mulhuddert), Astagob, etc. These names give an idea of the extent of the Castleknock estate, and at the same time show how thoroughly the district came into the power of the Norman occupiers, to the exclusion of the native Irish."