Flag of Munster

The flag of Munster consists of three gold crowns on a blue field. Similar crowns were included on the arms of Ireland before being superseded by the golden harp in the 16th century. The meaning of the crowns on the flag is not certain, but one possibility is that they may represent three of the medieval Hiberno-Norman lordships in Munster; the O’Briens (Thomond), the Butlers (Ormond) and the Fitzgeralds (Desmond).

For more than four hundred years, the Province of Munster has been heraldically symbolised by three golden antique crowns on a deep blue shield. The crowns may represent Thomond (Tuamhain, North Munster), Desmond (Deasumhain, South Munster), and Ormond (Urumhain, East Munster). While these arms are on record as relating to Munster as early as the sixteenth century, the motif, namely the antique Irish crown which inspired them, is considerably older. For example, a crown of the type now known as antique Irish, crafted in burnished metal and resting on a blue enamel surface, forms part of a thirteenth-century crozier head found near Cormac’s Chapel on the Rock of Cashel. This Gaelic Irish artifact is now in the National Museum of Ireland, Kildare Street, Dublin. Cashel was the seat of the Kings of Munster, from early Christian times through to the fifteenth century. In the case of the ‘king-bishops’ of Cashel, the placing of the antique crown on their crozier, could be interpreted as a symbolic assertion of their right to the political sovereignty of Munster. It is suggested therefore that the sovereignty of Munster, as expressed in heraldic format, uses the antique crown in triplicate. (Tripling of symbols in heraldic art is a convention used to achieve balance on the triangular surface of a shield.)

As to the tincture (colour) of the Munster shield, in Gaelic mythology the sovereignty of Munster was personified in Mór Muman – a lady or goddess dressed in deep blue robes.

The flag of Munster is usually displayed alongside the flags of Leinster, Ulster and Connacht, or as part of the combined flag of the Provinces of Ireland.

...
Wikipedia