As far as anyone can tell, the history of the Irish people began some 10,000 years ago. Previous to this point, it’s believed that Ireland was uninhabitable and that the first people to settle braved the Irish Sea in boats from Britain. Fast forward 5,000 years and evidence of a Neolithic people appear on the eastern side of the island, with stone monuments, burial grounds, housing and stone walls—for cultivating grains imported from the Iberian Peninsula. In the Bronze Age to follow, metalwork, crafts and increased stone constructions can be traced. Ireland was trading with Britain, Wales, France and Spain.
How the Celtic culture and languages emerged is debated, but it occurred during the Iron Age, possibly by either a large-scale migration of peoples from Europe or by the trickle of different peoples, influences, languages, ideas and cultures over a long period of time, mainly through Britain and northern parts of Europe.
In writing, Ireland is first mentioned as ‘Little Britain’ by Ptolemy, in his second-century geographic survey Almagest. England is referred to as Great Britain. The names simply denoted that one island was bigger than the other. The exact date Almagest was produced is unknown, but Ptolemy, who lived from 100 to 170, produced another survey in 150 titled Geography, in which he refers to Ireland as Iouernia and Great Britain as Albion. This is believed to be the way the people of Ireland pronounced it, instead of an observation made by Ptolemy. The Latinized version is Hibernia, which can still be seen in small use today, especially in referring to language, though some place names use the term.
Between its first mention by the outside world in the 100s and the consolidating kingdoms of Ireland in the 700s little is known. Roman coins have been found in settlements, but the amount of contact, culture, governance and agriculture, among other things, are not well documented or known. The kingdoms, which Ptolemy numbered at sixteen ruled Ireland as separate entities.
The concept of a High King of Ireland took hold by the 8th century, though a record of high kings stretches by centuries prior. This is believed to be fabricated to give weight to the idea. The kingdoms remained individual, though they were nominally devoted to the High Kingdom, which ruled over Meath, now County Meath—the Boyne Valley. The Hill of Tara became a significant place were kings were crowned, much like the Stone of Destiny in Scotland (Stone of Scone). The idea of a High King and actually having one installed waxed and waned over time.
During this time of kingdoms, there was an some governance over the whole of Ireland through the Early Irish Law, or Brehon law. It dealt with civil matters rather than criminal. Brehon law lasted until the Norman Invasion, but then gained ground again in the 13th to 17th centuries.
It was around this time that Christianity started to take hold in Ireland. If The Chronicle of Ireland is accurate, then Bishop Palladius started a mission in 431. However most believe Ireland’s patron saint, St. Patrick, began his missionary in 432. In 433, St. Patrick defied the High King’s command that only a fire at the Hill or Tara could burn during festival time, and started a paschal (Easter) fire on the Hill of Slane (although the exact location is debated). The High King was impressed by his defiance and Christianity started to rapidly take over pagan beliefs.
Ireland is well-known for its Christian scholars, who were able to preserve much of the understanding of Latin and Greek, while excelling in Christian arts, such as intricate carvings of Celtic crosses that still dot the landscape, and illuminated manuscripts, the most famous of which, and indeed one of the most important medieval books, The Book of Kells, was produced in the Boyne Valley. In this respect, Ireland did not succumb to the Dark Ages as the rest of Western civilization did after the fall of the Rome Empire.
Missionaries from Ireland were sent abroad, most notably St. Columba, who traveled to the isles of Scotland and founded a mission on Iona in 563. Missions spread Celtic Catholicism from Scotland to England and then to Europe up until the late Middle Ages.
Vikings raided Irish monasteries and towns from the Irish Sea starting in the 9th century. They also settled in Ireland and were involved in settlements such as Dublin, Cork, Wexford, Waterford and Limerick. The Vikings pushed further inland, as much of the country and waterways were easily navigable.
Eventually the Vikings, through settling and forming strongholds because to intermarry and form alliances with the Irish. These Vikings were mainly Norwegain. The culture of the Norse also intermingled with Irish culture.
But there were still skirmishes and battles through Ireland, with the Battle of Clontarf in 1014 being one of the last fought between the Irish and the Vikings. It would not be long after this battle that an invasion by the Normans would change the direction of Ireland for centuries.
See Ireland: A Brief Overview Part II: The Norman Invasion-Present