The ancient Gaelic septs of County Kildare were descended from Cathaoir Mor, King of Ireland, who died in 122 AD. The Ui Failghe (O’Connors Faly), ruled over the present day baronies of East and West Offaly and part of Laois. They lost some of their lands to the Fitzgeralds during the Anglo-Norman invasion, and the remainder during the plantations of Laois and Offaly. O’Connor comes from Conchobhar, meaning wolf-lover, which was quite a common early Irish name. From the Ui Failghe line evolved two prominent branches, the O’Dempseys, (from the Irish word diomasach, meaning proud) and the O’Dunnes, (from the Irish word donn, meaning brown-haired). Dunne is still a common name throughout County Kildare.
Within the territory of the O’Carey’s lived the native Gaelic Ó Tnúthghail Sept of North County Kildare who sometimes anglicized their name as Knowles as well as the more usual Newell.
The ecclesiastical division known as the parish of Rosenallis included all Mountmellilick from the Owenass River, Rearymore, Kilmanman and Castle brack comprises the territory of the O’Duinn Sept. This territory became known as the Barony of Tinnahinch.
An old pictorial map of Laois and Offaly printed in 1533, shows the present townland of Tinnahinch referred to as Bawn Regan. Bawn Regan was an earthen fort which was the headquarters and stronghold of the O’Dunnes. On this site was built Tinnahinch Castle in the early 13th century. Mention of this stronghold is found in the Annals of the Four Masters volume 5, page 1502.
This castle continued to be the major seat of the O’Dunnes until it was attacked in 1653 by the Cromwellian commander, Colonel Hewson. After strong resistance, the castle was surrendered. It was destroyed, and very little trace of the castle is to be seen today.
Other castles built in the region are. Castlebrack Castle built by Lenagh O’Doyne in 1427. Coolnamony Castle built by Teig Oge O’Doyne about 1551. Clarahill Castle built around 1600. Roskeen Castle in the possession of Donal O’Dunne in 1584. Ballynahimmey Castle. Ballinakill Castle built before 1594 and modified in 1680 by Colonel Terence O’Dunne.
When the Cromwellian War started in 1641, Daniel O’Dunne, Terence O’Dunne and most members of the Dunn Sept sided with the Confederate Catholics. Military defeats by the English destroyed most of the Dunn family holdings.
Source: Croasdaile’s History of Rosenallis, Co. Laois, Ireland. edited by Michael Merrigan, Dun Laoghaire Genealogical Society, 1998.