Mullach Abu meaning The Hills Forever is the O'Regan family motto.

The name Regan, O'Regan, Reagan is derived from its Irish language form O Riagain meaning "descendant of Riagan", a first name which is thought to derive from the word "ri" meaning king. The name is listed at number sixty six on the list of most common names in Ireland. It's abundance is due to the fact that the the name came not from one ancestor, but from several. One sept had its' origins in the Counties of Meath and Dublin of one of the Four Tribes of Tara.

The sept we are concerned with is descended from Donncuan, brother of the heroic Irish King, Brian Boru. King Brian was the last King of Ireland(as well as the first Christian) and an important historical fiqure in 1014 when he defeated the Danish and freed Ireland from their domination at the battle of Clontarf.

The Regan name is found in the Province of Munster, especially in the County of Cork. Regan's have been found in the north Cork Blackwater valley since the twelfth century and in the south Carbery region since the sixteenth century.

There are about 9000 Regans in Ireland with that number increasing 10 fold in areas all over the world due to the number who left their homeland for other parts of the world.