Callan was an early medieval cantred within the shire of Kilkenny,[9] and part of the historic kingdom of Osraige (Ossory).

[3] The barony was part of in the historic Gaelic kingdom of Osraige (Ossory) and the territory of the Ua Glóiairn clan of Callann.

[9][10] According to O'Heerin's Topographical Poem (1420)[10] at the time of the Norman invasion the area was the territory of the clan called the Ua Glóiairn of Callann.

[9][10] The Ó Glóiairn (O'Gloran) were chiefs of Callainn, the area of the "cantred of O'Glóiairn", lying on both sides of the King's River.

[14] In the 18th century County Kilkenny consisted of the Liberties of Kilkenny and of Callan and the baronies of Galmoy, Lower Ossory, Fassadinig, Cranagh, Shellilogher, Gowran, Kells, Knocktopher, Ida, Igrin, Iverk and Ibercon.

[9] By the 19th century these were restructured into the baronies of Callan, Crannagh, Fassadinin, Galmoy, Gowran, Ida, Iverk, Kells, Knocktopher, and Shillelogher.

[15] Callan lies to the west of the county, with the baronies of Shillelogher to the north and Kells to the south.