NOTE ON THE FORMATION OF COUNTIES
From A Concise History of Ireland by P. W. Joyce
THE division of Ireland into shires or counties is of Anglo-Norman and English origin. The counties generally represent the older native territories and sub-kingdoms.
King John, as has been already stated (238), formed twelve counties in 1210, namely Dublin, Kildare, Meath, Uriel (or Louth), Carlow, Kilkenny, Wexford, Waterford, Cork, Kerry, Limerick, and Tipperary. King's County and Queen's County were formed in the time of Queen Mary. Sir Henry Sidney, about 1565, formed the county Longford from the ancient district of Annaly. He also divided Connaught into six counties:—Galway, Sligo, Mayo, Roscommon, Leitrim, and Clare (but Clare was subsequently annexed to Munster, to which it had anciently belonged). Sir John Perrott, about 1584, formed the following seven counties of Ulster:—Armagh, Monaghan, Tyrone, Coleraine (now the county Derry), Donegal, Fermanagh, and Cavan: the other two Ulster counties, Antrim and Down, had been constituted some time before. This makes thirty, so far. In the time of Henry VIII, Meath was divided into two: Meath proper, and Westmeath. At first the county Dublin included Wicklow; but in 1605, under Sir Arthur Chichester, Wicklow was formed into a separate county. This makes the present number thirty-two.
END OF A CONCISE HISTORY OF IRELAND