County Sligo (/ˈslaɪɡoʊ/ SLY-goh, Irish: Contae Shligigh) is an Irish county and part of the province of Connacht. It is located in the Border Region. Sligo is the administrative capital and largest town in the county. Sligo County Council is the local authority for the county. The population of the county is 65,393 according to the 2011 census making it the 3rd most populated county in the province. It is noted for Benbulben Mountain, one of Ireland’s most distinctive natural landmarks.

The county was officially formed in 1585, but did not come into effect until the chaos of the Nine Years' War ended, in 1603. Its boundaries reflect the Ó Conchobhair Sligigh overlordship of Lower Connacht (Irish: Íochtar Connacht) as it was at the time of the Elizabethan conquest.

This overlordship consisted of the tuatha, or territories, of Cairbre Drumcliabh, Tír Fhíacrach Múaidhe, Tír Ollíol, Luíghne, Corann and Cúl ó bhFionn. Each of these was subsequently made into an English style barony: Carbury, Tireragh, Leyny, Tirerril, Corran and Coolavin. The capital of the newly shired county was placed at Sligo.

...
Wikipedia