Protohistory of Ireland in the context of Irish history

Gaelic Ireland (Irish: Éire Ghaelach) was the Gaelic political and social order, and associated culture, that existed in Ireland from the late prehistoric era until the 17th century. It comprised the whole island before Anglo-Normans conquered parts of Ireland in the 1170s. Thereafter, it comprised that part of the country not under foreign dominion at a given time (i.e. the part beyond The Pale). For most of its history, Gaelic Ireland was a "patchwork" hierarchy of territories ruled by a hierarchy of kings or chiefs, who were chosen or elected through tanistry. Warfare between these territories was common. Traditionally, a powerful ruler was acknowledged as High King of Ireland. Society was made up of clans and, like the rest of Europe, was structured hierarchically according to class. Throughout this period, the economy was mainly pastoral and money was generally not used. A Gaelic Irish style of dress, music, dance, sport and art can be identified, with Irish art later merging with Anglo-Saxon styles to create Insular art.

Gaelic Ireland was initially pagan and had an oral culture maintained by traditional Gaelic storytellers/historians, the seanchaidhthe. Writing, in the form of inscription in the ogham alphabet, began in the protohistoric period, perhaps as early as the 1st century. The conversion to Christianity, beginning in the 5th century, accompanied the introduction of literature. In the Middle Ages, Irish mythology and Brehon law were recorded by Irish monks, albeit partly Christianized. Gaelic Irish monasteries were important centres of learning. Irish missionaries and scholars were influential in western Europe and helped to spread Christianity to much of Britain and parts of mainland Europe.

The first evidence of human presence in Ireland dates to around 34,000 years ago, with further findings dating the presence of Homo sapiens to 7,000 BC. The receding of the ice the Younger Dryas cold phase of the Quaternary, around 9700 BC, heralds the beginning of Prehistoric Ireland, which includes the archaeological periods known as the Mesolithic, the Neolithic from about 4000 BC, and the Copper Age beginning around 2500 BC with the arrival of the Beaker Culture. The Irish Bronze Age proper begins around 2000 BC and ends with the arrival of the Iron Age of the Celtic Hallstatt culture, beginning about 600 BC. The subsequent La Tène culture brought new styles and practices by 300 BC.

Greek and Roman writers give some information about Ireland during the Classical period (see "protohistoric" period), by which time the island may be termed "Gaelic Ireland". By the late 4th century CE Christianity had begun to gradually subsume or replace the earlier Celtic polytheism. By the end of the 6th century, it had introduced writing along with a predominantly monastic Celtic Christian church, profoundly altering Irish society. Seafaring raiders and pirates from Scandinavia (later referred to as Vikings), settled from the late 8th century AD which resulted in extensive cultural interchange, as well as innovation in military and transport technology. Many of Ireland's towns were founded at this time as Scandinavian trading posts and coinage made its first appearance. Scandinavian penetration was limited and concentrated along coasts and rivers, and ceased to be a major threat to Gaelic culture after the Battle of Clontarf in 1014. The Norman invasion in 1169 resulted again in a partial conquest of the island and marked the beginning of more than 800 years of English political and military involvement in Ireland. Initially successful, Norman gains were rolled back over succeeding centuries as a Gaelic resurgence reestablished Gaelic cultural preeminence over most of the country, apart from the walled towns and the area around Dublin known as The Pale.