[3] She had seven brothers and one sister, four of which acceded to the Earldom of Desmond: The Annals of the Kingdom of Ireland by the Four Masters described her as "a charitable and truly hospitable woman".

This beautiful castle is situated about 1 mile (1.6 km) to the northeast of Rosscarbery (County Cork), in the bosom of a secluded valley shut in by hills and at one time by a dense plantation of trees.

Originally a strong structure, Benduff Castle was built in the usual style of the Norman fortresses which studded Ireland during the Middle Ages, distinguished for their square central keep or tower, with thick massive walls and loopholes for the use of arms as well as the admission of light, to which were generally attached side buildings furnished with bastions and strong outer walls enclosing the entire foundation — these latter being sometimes provided with covered ways.

The castle belonged to the clan of MacCarthy Gleannacroim, until about 1690, when it was forfeited due to the family supporting the Jacobite cause in the Williamite War in Ireland.

Leabhar Mhic Cárthaigh Riabhaigh was probably compiled to commemorate the marriage[7] of Finghin MacCarthy Reagh to Katherine, daughter of the 7th Earl of Desmond.

The book contains several important texts, including the new Ever-Tongue, a cosmological work, with a very important guide to the lives of saints including St. Bridget, St. Patrick and St. Columba, a translation of the travels of Marco Polo and one of the greatest compositions of the Fenian Cycle, the Acallam na Senórach or the Conversation Old Man.

Her eldest son, Donnell, seized the throne of Hy-Carbery after his uncle's death, some time before Katherine was dead.