For centuries before 1002 A.D., when Ireland was first united under King Brian Boru, the island had been divided into four rival kingdoms: Connaught, Leinster, Munster and Ulster. In general, a single powerful family or clan dominated each kingdom. At times, however, this family fought with rival families for domination, occasionally having to share dominion or even losing out entirely. When they weren’t fighting local rivals for control of their own lands, the rulers of each province were often trying to expand at one anther’s expense.

In time, the arms or heraldic symbols of each kingdom’s dominant family came to be linked with the kingdom it ruled, and are described and depicted:

Leinster

The emblem and flag of Leinster is a silver stringed golden harp (the Brian Boru harp) on a green field, dates from the 17th century or earlier. The Leinster flag was indistinguishable from the Green Flag which was the unofficial national flag of Ireland from 1798 until the early years of this century. A gold harp on a blue field (the Presidential Standard) had been the arms of Ireland since the 16th century, but the United Irishmen changed the colour of the field from blue to green - a colour which symbolised revolution in the late 18th century. The Green Flag was widely carried during the rebellion of 1798 - often with the motto of the United Irishmen, ‘Éire go brách’ (‘Ireland Forever’), below the harp.

Munster

The emblem and flag of Munster are three gold crowns on a blue field were the arms of Ireland before the adoption of the harp in the 16th century. The symbolism of the crowns on the Munster flag is not certain, but one possibility is that they may represent the three most important medieval lordships in the province - viz. those of the O’Briens (Thomond), of the Butlers (Ormond), and the Fitzgeralds (Desmond).

Connacht

The origin of the two elements displayed on the arms and glag of Connacht (Connaught) is obscure, but it is likely that the arm and sword derive from the arms of the O’Connors, the ruling family in the province before the Norman invasion, and that the black eagle derives from the arms of the Browns, one of the ‘tribes’ of Galway city. If this derivation is correct, the flag would be a symbol of the 17th-century unity of Gaels and Old English.

Ulster

The Ulster flag and emblem combines the emblem of the O’Neills of Tyrone, the red hand, with that of the de Burgos, a red cross on a gold field - the house to which the earldom of Ulster belonged until 1333 when the last de Burgo earl died.

With Ireland’s unification under King Brian and its gradual conquest by the Normans and English, the four kingdoms eventually disappeared as meaningful political or administrative units. But these centuries-old divisions had become ingrained. Even today, while they have little practical significance, Ireland’s traditional kingdoms live on in the island’s four provinces. Leinster, Munster and Connacht lie entirely within the Republic. Ulster’s nine counties are divided between the Republic, which includes three, and Northern Ireland, which contains the remaining six.

The traditional arms of the four provinces live on in the official arms of the Republic, where they are quartered together on a shield.

The heraldic harp is invariably used by the government, its agencies a its representatives at home and abroad. It is engraved on the seal matrix of the office of President as well as on the reverse of the coinage of the state. It is also emblazoned on the distinctive flag of the President of Ireland - a gold harp with silver strings on an azure field.

The model for the artistic representation of the heraldic harp is the fourteenth century harp now preserved in the Museum of Trinity College, Dublin, popularly known as the Brian Boru harp.