Ireland, sometimes known as the Republic of Ireland, was an island on Earth. It shared the island with Northern Ireland, which was a part of the United Kingdom until at least the 33rd century. (TV: The Beast Below)
During the late 10th and early 11th centuries, Ireland was the site of a major power struggle between the Norse King Sitric Silkbeard of Dublin and the Irish-born King Brian Boru of Munster. Following the first Leinster Revolt in 1000, Sitric's power was severely diminshed. In 1006, he lamented that he had become little more than a lapdog to Brian.
The Book of Kells was crucial to this power struggle. It was a powerful symbol of Irishness. Sitric was concerned that if Brian gained possession of the book, he would be able to use it to gain control of Dublin and Ireland as a whole. In 1006, he sent one of his warriors, Olaf Eriksson, to enlist the Abbey of Kells' chief librarian Brother Bernard's assistance in protecting the book so as to prevent Brian from using it as a pawn to place himself on the throne of Dublin.
Although Sitric's plan to keep the book out of Brian's hands was successful, his position was further destabilised by a second revolt in Leinster several years later and the Battle of Clontarf in 1014. The Eighth Doctor warned Brother Bernard to stay away from Clontarf during that year. (AUDIO: The Book of Kells)
In September 1649, the Seventh Doctor, Ace and Hex visited the Kingdom of Ireland during Oliver Cromwell's siege of Drogheda and Wexford. Hex's grandmother Hilda Schofield had previously told him about these incidents, which he described as being among the worst atrocities in Irish history. (AUDIO: The Settling)
Following the Glorious Revolution in November 1688, there were many deaths in Ireland. Jamie attempted to use this to justify altering history in an argument with the Second Doctor. (AUDIO: The Glorious Revolution)
In the 20th century, humans sometimes mistakenly assumed Gallifrey was a place in Ireland. (TV: The Hand of Fear, Human Nature; AUDIO: Fugitives) Andrew Harper made a similar assumption about Traken. (AUDIO: Autumn)