The Celts arrived in Ireland over the course of several centuries from around 500 BC; it was a gradual assimilation rather than an actual invasion. They brought with them the Gaelic language, fine artistry and a social order based on warrior values. They also brought the iron plough, which made it possible for the first time to cultivate the rich valley and lowland soils and form settled communities. By 250 AD, Celtic culture was in place across the entire island of Ireland.

Celtic society was hierarchical and class-based made up of extended families, or clanns, that were grouped together to form territorially based tribes, or tuath, ruled by a king or sometimes a queen. These were followed by a warrior aristocracy and grades of nobles. Druids, bards, filidh, judges and artisans formed the professional classes who enjoyed special privileges; they held positions of great importance sometimes undergoing years of intensive and difficult training. Under them were the freemen farmers who paid rent to the nobles. Agriculture was the basis of the Celtic economy and livestock played an essential role: cattle conferred prestige, serving as an equivalent to money and the Celt’s position in the social hierarchy was determined by the number of cattle he/she owned.

Iron Age Celtic lifestyles were not unsophisticated. The Celts were highly skilled artists, metal-smiths, miners, road-builders and farmers. Crafts such as cloth-weaving, basket-making, pottery and leather-working were mainly undertaken by women. They had strong trading links with Roman Britain and also traded for amber and precious metals as far as the Baltic coast and the Mediterranean.

Writing did not become highly developed until the arrival of Christianity and the Celts relied on the spoken word: their history, laws and culture were maintained orally by bards and druids and handed down the generations. Celtic spirituality was rooted in a reverence for the natural world, populated with many gods and goddesses and steeped in ritual. For the most part, they held to strict ideas about honour and responsibility. Celts took tremendous pride in their appearance and they were famous for their high spirits, love of liberty and courage in battle.

Ancient Irish myths describe a society dominated by the warrior hero. Single combat was one of the most effective ways for a warrior to gain status and prestige. Celtic warriors would sometimes charge into battle fully naked, dyed blue, and with great leaps and screaming cries could thoroughly unnerve their enemies. Celts were, at first, more advanced than the Romans with their superior chariots, shields and spears; they invented chain mail and iron helmets. They were so renowned that they served as elite troops in many foreign armies including those of Hannibal and the Egyptian pharaohs such as Cleopatra - she kept a band of 300 Celtic warriors as her personal bodyguards.

However, the Celts thought and acted as individuals rendering their armies fragmented and unstable. Despite their tremendous bravery in battle, they were no match for the war machine that was Rome which was far superior in organization, authority and discipline. Thus, Celtic Europe succumbed to the expanding Roman Empire; it was only by good fortune that Rome decided not to invade Ireland and the culture of the Celtic Irish continued to flourish.