High King of Ireland in the context of "Kingship of Tara"

The Gaels (/ɡeɪlz/ GAYLZ; Irish: Na Gaeil [n̪ˠə ˈɡeːlʲ]; Scottish Gaelic: Na Gàidheil [nə ˈkɛː.al]; Manx: Ny Gaeil [nə ˈɡeːl]) are an Insular Celtic ethnic group native to Ireland, Scotland, and the Isle of Man, and historically, Iceland and the Faroe Islands. They are associated with the Gaelic languages: a branch of the Celtic languages comprising Irish, Manx, and Scottish Gaelic.

Gaelic language and culture originated in Ireland, extending to Dál Riata in western Scotland. In antiquity, the Gaels traded with the Roman Empire and also raided Roman Britain. In the Middle Ages, Gaelic culture became dominant throughout the rest of Scotland and the Isle of Man. There was also some Gaelic settlement in Wales, as well as cultural influence through Celtic Christianity. In the Viking Age, small numbers of Vikings raided and settled in Gaelic lands, becoming the Norse-Gaels. In the 9th century, Dál Riata and Pictland merged to form the Gaelic Kingdom of Alba (Scotland). Meanwhile, Gaelic Ireland was made up of several kingdoms, with a High King often claiming lordship over them.

Monarchical systems of government have existed in Ireland from ancient times. This continued in all of Ireland until 1949, when the Republic of Ireland Act removed most of Ireland's residual ties to the British monarch. Northern Ireland, as part of the United Kingdom, remains under a monarchical system of government.

The office of High King of Ireland effectively ended with the Anglo-Norman invasion of Ireland (1169–1171) in which the island was declared a fief of the Holy See under the Lordship of the King of England. In practice, conquered territory was divided amongst various Anglo-Norman noble families who assumed title over both the land and the people with the prior Irish inhabitants being either displaced or subjugated under the previously alien system of serfdom. Though the revolutionary change in the status quo was undeniable, the Anglo-Norman invaders would fail to conquer many of the Gaelic kingdoms of Ireland, which continued to exist, often expanding for centuries after, however none could make any viable claims of High Kingship. This lasted until the Parliament of Ireland conferred the crown of Ireland upon King Henry VIII of England during the English Reformation. Henry initiated the Tudor conquest of Ireland which ended Gaelic political independence from the English monarch who now held the crowns of England and Ireland in a personal union.

The Anglo-Norman invasion of Ireland took place during the late 12th century, when Anglo-Normans and Cambro-Normans gradually conquered and acquired large swathes of land in Ireland over which the monarchs of England then claimed sovereignty. The Anglo-Normans claimed the invasion was sanctioned by the papal bull Laudabiliter. Gaelic Ireland then consisted of several kingdoms, with a High King claiming lordship over most of the other kings. The Anglo-Norman invasion was a watershed in Ireland's history, marking the beginning of almost 800 years of British presence in Ireland.

In May 1169, Anglo-Norman mercenaries landed in Ireland at the request of Diarmait mac Murchada (Dermot MacMurragh), the deposed King of Leinster, who sought their help in regaining his kingship. They achieved this within weeks and raided neighbouring kingdoms. This military intervention was sanctioned by King Henry II of England. In return, Diarmait had sworn loyalty to Henry and promised land to the Normans.

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.

Early Scandinavian Dublin was a major Viking settlement and pivotal center of Hiberno-Norse power in Ireland from its establishment in the mid-9th century until the Anglo-Norman invasion in 1170. The First Viking Age in Ireland began in 795, when Vikings began carrying out hit-and-run raids on Gaelic Irish coastal settlements. Over the following decades the raiding parties became bigger and better organized; inland settlements were targeted as well as coastal ones; and the raiders built naval encampments known as longphorts to allow them to remain in Ireland throughout the winter.

In the mid 9th century, Viking leader Turgeis or Thorgest founded a stronghold at Dublin, plundered Leinster and Meath, and raided other parts of Ireland. He was killed by the High King, Máel Sechnaill mac Máele Ruanaid, which was followed by several Irish victories against the Vikings and the seizure of Dublin in 849. Shortly after, a new group of Vikings known as the Dubgaill ("dark foreigners") came to Ireland and clashed with the earlier Viking settlers, now called the Finngaill ("fair foreigners").

Connacht, formerly also spelled Connaught (/ˈkɒnɔːt, ˈkɒnə(x)t/, Irish: Connachta [ˈkʊn̪ˠəxt̪ˠə] or Cúige Chonnacht [ˌkuːɟə ˈxʊn̪ˠəxt̪ˠ]), is the smallest and least populous of the four provinces of Ireland, situated in the west of Ireland. Until the ninth century it consisted of several independent major Gaelic kingdoms (Uí Fiachrach, Uí Briúin, Uí Maine, Conmhaícne, and Delbhna).

Between the reigns of Conchobar mac Taidg Mór (died 882) and his descendant, Aedh mac Ruaidri Ó Conchobair (reigned 1228–33), it became a kingdom under the rule of the Uí Briúin Aí dynasty, whose ruling sept adopted the surname Ua Conchobair. At its greatest extent, it incorporated the often independent Kingdom of Breifne, as well as vassalage from the lordships of western Mide and west Leinster. Two of its greatest kings, Tairrdelbach Ua Conchobair (1088–1156) and his son Ruaidri Ua Conchobair (c. 1115–1198) greatly expanded the kingdom's dominance, so much so that both became High King of Ireland.