The Celtic invasion of Ireland
From about 600 BC up to about the time of the birth of Christ, groups of invaders arrived in Ireland. These tall, fair-haired people came from the region around the Rhine and Danube rivers on the mainland of Europe, they were driven west by the advance of the Romans who called them Galli. Armed with iron swords they soon conquered the other peoples already in the country. Their language was an old form of what is now Irish.
The Celts were farmers who grew cereals and flax. They also spent much of their time tending large herds of cattle and sheep. They are said to have worn tunics or tight-fitting breeches and loose cloaks fastened with small iron brooches. Little is known of how the ordinary people lived, but Celtic kings dwelt in houses fortified by banks of earth, or in lake dwellings called crannog's
Little is known about Celtic religious beliefs. The Celts probably believed in a life after death, references in writings from the early Christian period refers to the Celtic Tir na nOg (land of youth) Roman's writing in Britain presented gruesome descriptions of Celtic sacrificial rituals, although these may have been embellished for propaganda reasons. The Celts appeared to have a reverence for nature, endowing certain places and objects with mystical significance, the oak tree appears to have been especially important to them, something the early Christian evangelists quickly turned to their advantage when choosing sites for their churches. The progression of the seasons were marked and celebrated at the festivals of Imbloc, Samhain, Their priests, called druids, also served as teachers, judges and advisors to the Kings.
The Celts divided the country into about 150 small communities called Tuatha. A king, called a Ri Tuatha, ruled over each Tuath. Sometimes a number of these kings recognized one of their number as an Árd Ri 'over king' and paid tribute to him. In the same way, a number of over kings formed a kind of federation under a king of one of the five provinces into which the country was divided. When Roman power in England was waning the Irish Celts made raids on England's western sea board for booty and slaves, it was probably one such raid in which St Patrick was carried off.
It is thought that at one time the Romans were poised to invade Ireland, but a revolt by one of its German legions stationed in Galloway caused them to postpone and finally cancel it