For much of this period, the island was divided into numerous clan territories and kingdoms (known as túatha). These túatha often competed for control of resources and thus they continually grew and shrank (in both size and number). In addition to kingdoms or túatha, Gaelic Ireland was also divided into five prime overkingdoms (Old Irish cóiceda, Modern Irish cúige). These were Ulaid (in the north), Connacht (in the west), Laighin (in the southeast), Mumhan (in the south) and Mide (in the centre).
Bhreathnach, Edel (ed.), The Kingship and Landscape of Tara. Four Courts Press for The Discovery Programme. 2005.
Byrne, Francis J., Irish Kings and High-Kings. Four Courts Press. 3rd edition, 2001.
Charles-Edwards, T.M., Early Christian Ireland. Cambridge University Press. 2000.
Curley, Walter J.P., Vanishing Kingdoms: The Irish Chiefs and their Families. Dublin: Lilliput Press. 2004.
Dillon, Myles, The Cycles of the Kings. Oxford. 1946. / Four Courts Press. Revised edition, 1995.
Duffy, Seán (ed.), Medieval Ireland: An Encyclopedia. Routledge. 2005.
Keating, Geoffrey, with David Comyn and Patrick S. Dinneen (trans.), The History of Ireland by Geoffrey Keating. 4 Vols. London: David Nutt for the Irish Texts Society. 1902-14.
MacKillop, James, A Dictionary of Celtic Mythology. Oxford. 1998.
Koch, John T. (ed.), Celtic Culture: A Historical Encyclopedia. 5 volumes or single ebook. ABC-CLIO. 2006.
Lalor, Brian, The Encyclopedia of Ireland. Yale University Press. 2003.
Mac Niocaill, Gearóid, Ireland before the Vikings. Dublin: Gill and Macmillan. 1972.
