County Offaly which had declined following the Norman Conquest of Ireland. Both Laois (Leix) and Offaly (Uí Failghe) were petty kingdoms in Gaelic Ireland located just outside the Pale (a region around Dublin and the mid east of Ireland that remained loyal to the English Crown following the Norman Conquest). The older kingdoms of Leix and Uí Failghe are not coterminous with the present day counties that were formed. The Kingdom of Uí Failghe from which the name Offaly is derived, was ruled by the Ó Conchobhair Failghe (anglicised as: O'Conor Faly) whose territory extended from the east of the county into
County Cavan springs near Bailieborough; the River Annalee which flows from Lough Sillan and joins the Erne; and the Cladagh river which rises from Cuilcagh and flows into Fermanagh. The Glyde and the Owenroe also source in Cavan. Cavan is known as 'The Lakeland County' and is reputed to contain 365 lakes. At , Lough Sheelin is the county's largest lake; it is situated in the south of the county and forms a three way border on its waters between counties Meath, Westmeath and Cavan. A large complex of lakes form in the north and west of Cavan into designated Specially Protected