12th March 2021 - I have just discovered the answer to a centuries old mystery: the exact location of the Kingdom of Cualann!
The exact Location of the Kingdom of Fera Cuala:
The Kingdom of the Uí Briúin Cualann has as it's centre point ÓCualann - the Great Sugar loaf. Take the mid-point from Glaskenny in Enniskerry to Windgates and run a line 5 miles long to Old Downs Rd. Run another line from the Little Sugar loaf through the Summit of Ó Cualann (Great Sugar Loaf) for 5 miles to Powerscourt Waterfall.
The following townlands are mentioned - the names in brackets are suggestions which I'll have to research more:
Barnecullen - Barnacoille Commons
Glassyn-kie - Glaskenny
Windgates - Windgates
Included in the Kingdom:
Beanaghabegge - Bahana
Benaghmore - (Barnamire?)
Onenaghe - Oonagh
Ballycortie - (Ballycorus?/ Ballycoyle?)
Templeregan - (Ballyremon?)
Kiltagarrane - (Curtlestown?)
Cokiston - Cookstown
Ancrewyn - Annacrivey
Killmolinkey - Kilmalin
Ballynbrowne - (Ballybawn?)
Killegar - Killegar
Mainistir - Monastery
Here is the source: John O'Donovan's 1847 translation of Leabhar na nGeart - The Book Of Rights, an ancient Irish text.
In his notes O'Donovan references Tirlagh O'Toole's 1636 appeals to the King to return the ancient land of Cuala which belonged to his forefathers.
Note the reference to "villages and craggs recte creaghts of old time" old places which had been long lost by 1636 - but which O'Toole's family clearly knew about.
Cualann - The situation and extent of this territory have been strangely mistaken by modern Irish writers But we have evidences which will leave no doubt as to its exact situation for in the Feilire Ænguis the churches of Tigh Conaill Tigh mic Dimmai and Dun mor are placed in Cualann And in an inquisition taken at Wicklow on the 21st of April 1636 the limits of Fercoulen i e Feara Cualann are defined as follows The said Tirlagh O Toole humbly desireth of his Majestie to have a certain territory of land called Fercoulen which his ancestors had till they were expulsed by the earls of Kildare That the said territory containeth in length from Barnecullen by east and south and Glassyn kie to Pollcallon by west the wind gates viz five miles in length and four in breadth being the more part mountaines woods and rocks and the other parte good fertile lands Within the said territory were certain villages and craggs recte creaghts of old tyme being now all desolate excepte onely Powerscourt Killcollin Beanaghebegge Benaghmor the Onenaghe Ballycortie Templeregan Kiltagarrane Cokiston Ancrewyn Killmollinky Ballynbrowne Killeger and the Mainster From this description of the territory the Feara Cualann it is quite evident that it was then considered as coextensive with the half barony of Rathdown in the north of the county of Wicklow and adjoining the county of Dublin