Archeological excavation provides evidence for the lifestyle of the peoples of pre-historic Ireland. The type of monument which more than any other is traditionally believed to have had its origins in the Celtic Iron age is the hillfort, ringfort, or dun. In its loosest context, these 'forts' are merely the stackyard enclosure of a farming family within which was the circular dwelling house or houses of planks or wattle and the animal shelters, farmyards, or stockades. Most hilltop sites would have an area enclosed with one or several bank of earth and rubble, faced originally with stone. The focus of the settlement was a circular house or houses, or, as at Navan Fort, identified with Emain Macha, the one-time capital of Ulster, a large mound crowning the hill, traditionally associated with the ancient seat or dwelling of the people of Ulster. Artifacts at various sites indicate the existence of workshops or smithys both for bronze and early iron-work, as well as spindles, jewelry, horsebits, and other evidence of domestic life.
Aside from limited archeological evidence, the picture of ancient Ireland is obscure. Source texts, written down from oral transmission in the early to late Middle Ages are suspect with regard to information about a society more than 1,000 years earlier. However, the learned class in Ireland was charged with the preservation in oral form from one generation to the next of a considerable body of material in which the tales, poems, genealogies, eulogies, and even the laws of society were enshrined. The laws were first written down in the 7th century or late 6th and in the 8th they were codified. The structure outlined in the law tracts is basically the same as that of the continental Celts of nearly a millennium earlier. The law tracts are therefore an indication of the longevity of oral tradition as fostered and preserved by the learned class, and there is nothing inherently improbable in proposing a 1st century or earlier date for the sagas also.
Just as the Irish law tracts mirror many aspects of the society of Continental Gaul as revealed by the classical writers, so are the Irish heroic tales regarding as bearing witness to an earlier age when a type of warrior society existed in Ireland comparable to that of Gaul in the 3rd and 4th centuries BC. Particular importance is attached to practices such as fighting from war-chariots, to boasting and duelling before battle, to feasting and to the 'champion's portion', cattle-raiding, beheading, and individual weapons.
In preliterate days, Irish society was structured according to nobles, a learned class and freemen. The Irish learned class, the aes dana, comprising poets, storytellers, lawyers, historians, wise men, and many other grades, had its counterpart in the druids of Gaul. The name druid was more or less interchangeable with fili, meaning wise man or seer. There is little information on how a druid was trained. From various accounts, a druid seems to have had one or more students attached to his retinue or household. The method of teaching was oral instruction: long lists and correspondences were learned by heart, but this theoretical teaching was undoubtedly supplemented by practical knowledge also. Another word held in common in Ireland and Gaul was bard, meaning 'the learned man in his function as the praiser of great men'. The Irish aristocratic privileged learned class preserved its records and promulgated its lore in oral form in the same manner as did its Gaulish counterpart.
Perhaps more than any other people, the Celts have always cherished the Otherworld. Very often the mound is a place of entry or a natural boundary where both worlds meet. Many gifts pass between mortals and the Otherworld folk. Most frequently, it is the faery mounds, which are designated homes of the Sidhe or Otherworldly beings. These are well-known and carefully avoided by those who fear the power of the Otherworld. The inner world of the sidhe is famous for its women, known as bean-sidhe or banshees as they become in later tradition. Although early Irish society was male-dominated, women had a prominent role in the literature and while the male heroes were idealized portraits of human warriors, women dominated the world of the supernatural. Since the period in which the tales were committed to writing was Christian, the goddesses were no longer worshipped, and their role in the literature became a non-religious one. Some goddesses were euhemerized; that is, they were made into pseudo-historical queens and tribal ancestors. Other goddesses became fairies or saints.