As with there Scottihs brethren the Irish have had an established and strong clan system. This comes from the influence of the Vikings, who also had a huge hand in the development of Scotland as well. Ireland was split up into 9 counties of varying size and power. These were Munster, Leinster, Connacht, Breifne, Airgallia, Ui Neill (North and South), Uliad and the Osraige. The formation of Northern Ireland and Ulster (from Ui Neill) has made this even more complicated. The main reason was that with so many Macs (son of) there had to be a plural. The word Clan comes from the Latin for offshoot. The logical progression can easily be seen.
The overall leadership of the clan system was transferred to the High King. This was largely a symbolic role as the Clan that held the most power was in a state of flux via economics and war. The Clan leaders or Taoiseach to give them the proper Gallic title, were the real power brokers. The fact that the Taoiseach is given to the head of the modern Government shows how important they were.
The intervention of the English Settlers and the enforcement of English common law on the land after the Act of Union saw the demise of the Clan system. This has caused much in the way of conflict but the Irish retain their independence. A fact that can be seen via it’s strong culture like the Aran Sweaters from Shamrock Gift.