Ireland has been inhabited since Stone Age times. For more than five thousand years peoples moving westwards across the European continent have settled in the country and each new group of immigrants, Celts, Vikings, Normans, English, has contributed to its present population.

In the Stone and Bronze Ages, Ireland was inhabited by Picts in the north and a people called the Erainn in the south, the same stock, apparently, as in all the isles before the Anglo-Saxon invasion of Britain. About the 4th century B.C., tall, red-haired Celts arrived from Gaul or Galicia and established their distinctive culture , although they do not seem to have come in great numbers. Ancient Irish legend tells of four successive peoples who invaded the country?the Firbolgs, the Fomors, the Tuatha De Danann, and the Milesians.

The Irish mythological cycle, which seems to be a history of this period, can be divided into four major divisions. The first is the historical-mythological cycle. Two important texts are part of this cycle: the Leabhar Gahbala (Book of Invasions), a mythological history of Ireland; and the Dinnshenchas (History of Places), a mythological geography of Ireland. The main theme in the historical-mythological cycle concerns the peopling of Ireland and the fortunes of the Tuatha De Danann (People of the Goddess Danann), who were the mythological ancestors of the Irish.

In the historical-mythological cycle the story of the predecessors of the Irish settlement is told. The first group to come to Ireland is led by a woman, Cesair; the majority of her group is composed of women. This group arrives before the great flood, and all are destroyed in the flood except one, Fintan, who in the form of a salmon, eagle, or hawk witnesses all of the later settlements. Fintan is the patron of the traditional lore and storytelling. The next group is led by Partholan, but he and all of his people die in a plague. A third group is led by Nemed; after suffering many vicissitudes, this group divides into three parts and abandons Ireland. Two of these groups, the Fir Bolg (Bolg Men) and the Tuatha De Danann (People of the Goddess Danann), occupy the subsequent history. The Fir Bolg return to Ireland, which they divide into the five provinces of Ulster, Leinster, Munster, Connacht, and Meath; they also introduce kingship. When the Tuatha De Danann arrive, warfare ensues over possession of the land. One tradition states that after the First Battle of Mag Tuired, the Fir Bolg and Tuatha De Danann make peace and agree to live together in harmony.

The Tuatha are described as demigods; they are beautiful people, possessed with skill in music and the arts. They are always spoken about within a context of fabulous magical powers and wonders, which define the essence of their manifestation. A central theme in the myth of the Tuatha is that of the Second Battle of Mag Tuired. During the First Battle of Mag Tuired the king of the Tuatha, Nuada, is wounded. Because he is now physically blemished, he can no longer serve as king. The kingship is then given to his adopted son, Bres. Bres's father is a king of the Fomoire, a group of people with whom Nemed and his people had fought in previous times. Bres's mother, Eriu, is, however, a Tuatha. The choice of Bres is apparently an attempt to accomplish an alliance between the Tuatha and the Fomoire.

The Tuatha are themselves later defeated by the Sons of Mil, the immediate ancestors of the Irish people. The Tuatha are said now to live in the underground of Ireland, in the fairy regions, where the fairies are subject to them.

The second division is the Ulster cycle. These myths are stories of the warriors of King Conchobar. The themes of those of honor and prestige revolve around heroic deeds and the hero Cu Chulainn (or Cuchulainn).

The third division is that of Fenian. The Fenian Cycle recounts the exploits of Finn Mac Cumhail and his companions and deals with the cult and institution of warriors.

The last division deals with the institution and founding of the great and lesser kings of Ireland.

Oddly enough, the Romans, who occupied Britain for 400 years, never came to Ireland, and the Anglo-Saxon invaders of Britain, who largely replaced the Celtic population there, did not greatly affect Ireland.

The earliest settlers arrived around 7,000 BC in the Mesolithic or middle stone-age period. They arrived in the north across the narrow strait from Britain. These people were mainly hunters.

Colonists of the Neolithic, or new stone-age, period reached Ireland around 3,000 BC. These were farmers who raised animals and cultivated the soil. Many remnants of their civilisation - houses, pottery, implements have been excavated at Lough Gur in Co. Limerick and some can be seen at the folk park now developed around the lakeside site.

The Neolithic colonists were largely self-sufficient but engaged in a limited form of trading in products such as axe-heads. Many of their religious monuments have survived, the most impressive of which is the great megalithic tomb at Newgrange in Co. Meath.

Prospectors and metalworkers arrived about 2,000 BC. Metal deposits were discovered and soon bronze and gold objects were being manufactured. Many artefacts made by these bronze-age people have been found, among them axe-heads, pottery and jewellery.

About 1,200 BC another movement of people reached Ireland, producing an even greater variety of weapons and artefacts. A common type of dwelling in use at this time was the crann�g, an artificial island, palisaded on all sides, constructed in the middle of a lake.

The people who made the greatest impact on Ireland were the Celts. The earliest waves of Celtic invaders may have reached the country from central Europe as early as the 6th century BC with subsequent groups arriving up to the time of Christ. The Celts belonged linguistically to the great Indo-European family. They soon came to dominate Ireland and it's earlier settlers. The Celtic culture of the La Tene civilisation - named after a Celtic site in Switzerland - reached Ireland around the 2nd century BC. Celtic Ireland was not unified politically, only by culture and language. The country was divided into about 150 miniature kingdoms, each called a tuath. A minor king ruled a tuath, subject to a more powerful king who ruled a group of tuatha, who was in turn subject to one of the five provincial kings. This political situation was very fluid, with constant shifts in power among the most important contenders.

Celtic Ireland had a simple agrarian economy. No coins were used and the unit of exchange was the cow. People lived on individual farms and there were no towns. Society was rigidly stratified into classes and was regulated by the Brehon Laws, an elaborate code of legislation based largely on the concepts of the tuath as the political unit and the fine, or extended family, as the social unit.

Christianity was introduced in the 5th century. This is traditionally associated with St Patrick (d. 461) although there were some Christians in the country before his arrival. The first written documents date from this period.

A distinctive feature of the development of early Irish Christianity was the important role played by monasticism. The great monasteries such as Glendalough, founded by St Kevin, and Clonmacnoise, founded by St Ciaran, were famous centres of culture and learning and the illuminated manuscripts which they produced were among the glories of Irish monasticism. It was through the monasteries that Irish influence on Britain and Europe was exerted from the 6th century onwards.

Setting out first as pilgrims, Irish monks preached the Gospel and established new communities across the continent. Ireland, unlike most of the rest of Europe, did not suffer barbarian invasion and so acted as a repository of Christian civilisation at a time when it was almost extinguished elsewhere.

Irish monks are associated with a number of continental centres - St Fursey at Peronne in France, St Kilian at Wurzburg in Germany, St Vergil at Salzburg in Austria, St Columbanus at Bobbio in Italy. They brought Christianity to pagan peoples, established centres of learning and paved the way for the intellectual flowering in 9th century France known as the Carolingian Renaissance. One of the most notable of these monks was the philosopher and theologian Johannes Scotus Eriugena.

The successful missionary efforts of the Irish abroad were matched by rich cultural achievements at home. Elaborate chalices, croziers and ornamental jewellery were fashioned while the scribes committed the rich classical tradition to their magnificently illuminated manuscripts. This period from the 6th to the 9th century has been seen by many as the Golden Age of Irish history.