The Clan/Sept History

The name O'Shea is one of several transliterations of the Gaelic 'O'Seaghdha,' meaning 'descendant of Segda.' The Segda, or Seghdha, in question was a 7th-century Chieftain of the Corcu Duibne kin group (which also produced the septs of O'Connell and O'Falvey), a western Kerry tribal group which can be identified at least as early as the 6th or 7th century in western Kerry, and which may be synonymous with the 'Iverni' described by Ptolemy in his outline of Ireland given in the mid-2nd century (note the similary between 'Iverni' and Uibh Rathach, or 'Iveragh,' of which the O'Sheas were Lords until the 12th century). The most extensive information on this Seghdha (although, one expects, mostly the product of 12th-century synthetic historians) may be found in the 'Caithreim Ceallachain Chaisil,' a 12th-century propaganda text written for King Cormac III MacCarthy of Munster.